Abstract:
A computer program debugger is disclosed which stores previous programs which have been debugged and the debug parameters which were considered when debugging. When a new computer program is to be debugged, the new debugger is invoked and it automatically compares the executing program to be debugged with the previous programs. When one or more of the debug parameters are so similar that it can be said that the computer program undergoing debugging matches a previously stored computer program, a user is given options to display the matching programs, the modules, the functions, the lines, and the debug parameters and to exchange debug parameters between the programs which can be used to modify the either or any of the programs. The user is further given the option to store the current program undergoing debugging as a new program to be considered in matching the next program to be debugged. It is further envisioned that the various debug scenarios may be stored and can be recalled separately from the program that generates or uses them.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to the field of computer programs, and more particularly, relates to an algorithm which compares scenarios during a debug session of a computer process and matches the current scenario with a preexisting scenario or establishes a new scenario if no preexisting scenario matches.  
         BACKGROUND OF THE INVENTION  
         [0002]    An important aspect of the design and development of a computer program is debugging which is intended to locate and identify errors in a computer program under development. Typically, a programmer uses another computer program commonly known as a “debugger” to debug a program under development. Conventional debuggers typically support two primary operations to assist a computer programmer. A first operation supported by conventional debuggers is a step function which permits a computer programmer to process instructions, also known as statements, one at a time in a computer program and see the results of each instruction upon completion. While the step operation provides a programmer with a large amount of information about a program during its execution, stepping through hundreds or thousands of program instructions is tedious and time consuming. The programmer may be required to step through many program instructions that are already known to be error-free before a set of instructions to be analyzed are executed.  
           [0003]    To address this difficulty, a second operation supported by conventional debuggers is the breakpoint operation which permits a computer programmer to identify a breakpoint as a precise instruction at which execution of a computer program is halted. As a computer program is executed by a debugger, the program executes in a normal fashion until a breakpoint is reached, the program stops execution and the debugger displays the results of the computer program to the programmer for analysis.  
           [0004]    Step operations and breakpoints are typically used together to simplify the debugging process. Specifically, a user during a common debugging operation will set a breakpoint at the beginning of a desired set of instructions to be analyzed and then begin execution of the program undergoing debugging. Execution halts at a breakpoint and the programmer then steps through the desired set of instructions line-by-line using the step operation. Consequently, a programmer is able to quickly isolate and analyze a particular set of instructions without having to step through irrelevant portions of a computer program.  
           [0005]    Most breakpoints supported by conventional debuggers are unconditional meaning that once such a breakpoint is reached, execution of the program is always halted. Some debuggers, however, also support the use of conditional breakpoints which only halt execution of a program when a variable used by the program is set to a predetermined value at the time such a breakpoint is reached. One significant drawback to conventional breakpoints results from the fact that some instructions in a computer program are executed fairly often for different purposes and may result in many needless stoppages before a desired stoppage is encountered. This problem is especially pronounced in object-oriented programming (OOP) and other highly modular languages where a single general purpose portion of a computer program may be executed in many different situations for different purposes.  
           [0006]    With an object-oriented programming language, for example, a program is constructed from a number of “objects,” each of which includes data and/or one or more sets of instructions, often referred to as routines or methods that define specific operations that can be performed on the data. A large number of objects may be used to build a computer program with each object interacting with other objects in the computer program to perform desired operations. When one object invokes a particular routine in another object, the former object is often said to be calling the routine in the latter object. Some general purpose objects in a computer program may support basic operations, e.g., displaying information to a user, printing information on a printer, storing or retrieving information from a database, etc. Particularly, these generic type of objects are called by many different objects so that placing a conventional breakpoint in a routine of one of these common generic objects will result in hundreds of unwanted stoppages prior to occurrence of a desired stoppage. Thus, context sensitive breakpoints can be set in certain debuggers to retrieve the sequence of routines in the computer program that are called just prior to reaching the breakpoint, such as in U.S. Pat. No. 6,077,312 entitled “Apparatus, Program Product and Method of Debugging Utilizing a Context Sensitive Breakpoint” issued Jun. 20, 2000, commonly owned by the assignee and herein incorporated by reference in its entirety. Context sensitive breakpoints locate the specific calls in other objects that relate to the desired stoppage in a particular object. This eliminates the extremely time consuming and tedious task of setting each breakpoint and eliminates the risk that not all relevant calls are located so not all desired circumstances for inducing stoppages may be recognized during debugging.  
           [0007]    But, setting breakpoints and halting execution of a program undergoing debugging is still onerous. Significant time is spent going through the breakpoints, whether the breakpoints are general or are context specific, as above. Merely watching breakpoints, moreover, does not solve the problem of determining the dynamics of an executing program in which variables and other expressions stored in a memory location may constantly change. These changing variables, moreover, may have either a direct or an indirect impact on other variables and other computer expressions.  
           [0008]    As an example, if a user sets a breakpoint at line  12  in procedure A, she/he almost always sets a breakpoint at line  40  in some procedure B also because this is where some particular data she/he is interested in is processed. In fact, this occurrence is so common that one of the most popular features of debuggers today is to allow users to save their debug environment and restore it the next time they start debugging. While this is helpful to those users who start debugging one problem and have to stop and resume debugging later, it seldom helps the user to debug a similar problem the next time and the user must establish the same breakpoints and program variable monitors again. How a user got to a particular environment is not at all obvious; there may be different codes acting on different structures. Once a user sets breakpoints, moreover, the breakpoints must be managed meaningfully.  
           [0009]    In addition, contemporary debuggers usually associate an environment instance with a specific program. While this works in some situations, it is of little help in others, especially where the same objects are called in other programs. Similarly, if a user would like to debug a specific process or job on a target machine, but doesn&#39;t know the program name on that machine, it may be difficult, if not impossible, to restore a debugging environment from the previous debug session.  
           [0010]    There is thus a significant need in the industry to help programmers establish important breakpoint and monitor scenarios and to be able to recall these scenarios across different programs that are debugged.  
         SUMMARY OF THE INVENTION  
         [0011]    These needs and others that will become apparent to one skilled in the art are satisfied by a matching algorithm which determines what restorable debug entities comprise a scenario of a computer program, assigns an individual weight to each of the restorable debug entities; and then, given any two scenarios, comparing the restorable debug entities of each scenario to determine the extent of similarity between the scenarios. If the scenarios are significantly different, the algorithm will establish and store a new scenario. It is further contemplated that the algorithm recognizes that a previous scenario has been stored. The previous scenario may then be restored. The current scenario may be modified by incorporating the debug entities of the previous scenario; or the previous scenario may be modified by incorporating the debug entities of the existing scenario.  
           [0012]    The restorable debug entities may comprise at least one breakpoint and/or a location of the at least one breakpoint in any two scenarios. The breakpoints may be either a line and/or an exit breakpoint. Another restorable debug entity may be an operation and/or its location in any two scenarios. Yet other restorable debug entities may comprise one or more expressions and/or a location and/or a value of the expressions in any two scenarios.  
           [0013]    It is further envisioned that the invention is a matching algorithm, comprising: determining that a scenario may comprise a plurality of restorable debug entities, each of which may further comprise one or more of the following: at least one breakpoint and/or a location of the at least one breakpoint, at least one operation and/or a location of the at least one operation, at least one expression and/or a location and/or a value of the at least one expression; assigning an individual weight to each of the restorable debug entities; given a current scenario and at least one previous scenario, comparing the restorable debug entities of the current scenario to the restorable debug entities of at least one previous scenario to determine the extent of similarity between the scenarios; establishing and storing the current scenario if the scenarios are different; recognizing that a previous scenario has been stored; restoring the previous scenario; and modifying the current scenario by incorporating the debug entities of the previous scenario and/or modifying the previous scenario by incorporating the debug entities of the current scenario.  
           [0014]    The invention is also a method of debugging a computer program, comprising the steps of: monitoring a number of parameters that can be used to debug a computer program; comparing at least one environment in which at least one of the parameters are referenced during the execution of the program; determining that the at least one environment is similar to an executing portion of the computer program because of a similarity of at least one of the parameters; and retrieving and displaying the at least one similar environment and the at least one and other parameters, if any, of the similar environment. The step of determining may further comprise weighting each of the parameters; summing each of the weighted parameters; and then determining if the sum of the weighted parameters is greater than or equal to a threshold value of similarity. The method may also include the steps of retrieving and displaying all of the similar environments and parameters of the similar environments wherein the parameters are similar beyond the threshold value of similarity. The computer program and/or the environment may be modified as a result of the step of comparison. The method may also store that executing portion of the computer program as a new environment if the executing portion of the program is less than the threshold value of similarity.  
           [0015]    The invention is also an article of manufacture, comprising a data storage medium tangibly embodying a program of machine readable instructions executable by an electronic processing apparatus to perform method steps for operating an electronic processing apparatus, said method steps comprising the steps of: initiating a user interface to invoke execution of a computer program undergoing debugging; determining a plurality of debug entities to monitor during the execution of the computer program; monitoring the plurality of debug entities during execution of the computer program; recalling a plurality of scenarios having some of the same plurality of debug entities as those of the executing computer program; comparing the debug entities of the plurality of scenarios with the plurality of debug entities of the executing computer program; determining if any of the plurality of scenarios match the executing program based on the similarity of the debug entities; and displaying those scenarios and debug entities of the displayed scenarios that match the debug entities of the executing computer program. The article of manufacture may further cause the executing computer program to be modified. The executing computer program may be stored as a new scenario if no matching scenarios exist.  
           [0016]    The invention is also an article of manufacture, comprising a data storage medium tangibly embodying a program of machine readable instructions executable by an electronic processing apparatus, comprising: a plurality of potentially matching scenarios which, when compared to a computer program undergoing debugging, may indicate that the computer program is equal to or greater than a threshold value of similarity to at least one of the matching scenarios.  
           [0017]    The invention is also a computer program debugger, comprising a means to call a computer program; a means to set a plurality of debug parameters to monitor during execution of the computer program; a means to store a plurality of scenarios of previously executed computer programs, each of said scenarios having at least one debug parameter; a means to compare the debug parameters of the computer program during execution with the debug parameters of the previously executed computer programs; a means to ascertain whether the computer program is similar to any of the previously executed computer programs; a means to display the previously executed computer programs that are similar to the computer program; a means to modify the computer program in accordance with any of the similar previously executed computer programs; and a means to store the computer program and its debug parameters.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0018]    The novel features believed characteristic of the invention are set forth in the claims. The invention itself, however, as well as a preferred mode of use, objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying Drawing, wherein:  
         [0019]    [0019]FIG. 1 is a high-level block diagram of a server computer system capable of implementing the preferred embodiment of the invention.  
         [0020]    [0020]FIG. 2 is a simplified representation of a computer network capable of implementing the preferred embodiment of the invention.  
         [0021]    [0021]FIG. 3 is a representation of a graphical user interface of how to establish weights of various factors in a debugging scenario in accordance with an embodiment of the invention.  
         [0022]    [0022]FIG. 4 is a representation of a graphical user interface illustrating potentially matching scenarios in accordance with an embodiment of the invention.  
         [0023]    [0023]FIG. 5 is a representation of a graphical user interface of potentially matching scenarios and their attributes. It is suggested that FIG. 5 be printed on the face of the patent.  
         [0024]    [0024]FIG. 6 represents a data structure of scenarios which match a current scenario in accordance with an embodiment of the invention.  
         [0025]    [0025]FIG. 7 represents a data structure of debug entity records in which various attributes match the current debug scenario in accordance with an embodiment of the invention.  
         [0026]    FIGS.  8 - 11  are flowcharts illustrating the program flow of the method to create and/or match a new debug scenario with a new or preexisting scenario in accordance with an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    Referring to the Drawing, wherein like numbers denote like parts throughout the several views, FIG. 1 illustrates a computer system  10  consistent with the invention. Computer system  10  is illustrated as a networked computer system including one or more client computers  12 ,  14  and  20 , e.g., desktop or PC-based computers, workstations, etc., coupled to server  16 , which could also be a PC-based server, a minicomputer, a midrange computer, a mainframe computer, etc., through a network  18 . Network  18  may represent practically any type of networked interconnection, including but not limited to local-area, wide-area, wireless, and public networks such as the Internet. Any number of computers and other devices may be networked through network  18 , e.g., multiple servers.  
         [0028]    Client computer  20 , which may be similar to computers  12 ,  14 , may include a central processing unit (CPU)  21 ; a number of peripheral components such as a computer display  22 ; a storage device  23 ; a printer  24 ; and various input devices, e.g., a mouse  26  and keyboard  27 , among others. Server computer  16  may be similarly configured, albeit typically with greater processing performance and storage capacity, as is well known in the art.  
         [0029]    [0029]FIG. 2 illustrates in another way an exemplary hardware and software environment may be configured for an apparatus  30  consistent with the invention. For the purposes of the invention, apparatus  30  may represent practically any type of computer, computer system or other programmable electronic device, including a client computer, e.g., similar to computers  12 , 14  and  20  of FIG. 1, a server computer, e.g., similar to server  16  of FIG. 1, a portable computer, an embedded controller, etc. Apparatus  30  may be coupled in a network as shown in FIG. 1, or may be a stand-alone device in the alternative. Apparatus  30  will hereinafter also be referred to as a computer although it should be appreciated the term “apparatus” may also include other suitable programmable electronic devices consistent with the invention.  
         [0030]    Computer  30  typically includes at least one processor  31  coupled to a memory  32 . Processor  31  may represent one or more processors or microprocessors, and memory  32  may represent the random access memory (RAM) devices comprising the main storage of computer  30 , as well as any supplemental levels of memory, e.g., cache memories, nonvolatile or backup memories, programmable or flash memories, read-only memories, etc. In addition, memory  32  may be considered to include memory storage physically located elsewhere in computer  30 , e.g., any cache memory in a processor  31 , as well as any storage capacity used as a virtual memory, e.g., as stored on a mass storage device  36  or on another computer coupled to computer  30  via network  38 .  
         [0031]    Computer  30  also typically receives a number of inputs and outputs for communicating information externally. For interface with a user or operator, computer  30  typically includes one or more user input devices  33 , e.g., a keyboard, a mouse, a trackball, a joystick, a touchpad, and/or a microphone, among others, and a display  34  such as a CRT monitor, an LCD display panel, and/or a speaker, among others. It should be appreciated, however, that with some implementations of computer  30 , e.g., some server implementations, direct user input and output may not be supported by the computer.  
         [0032]    For additional storage, computer  30  may also include one or more mass storage devices  36 , e.g., a floppy or other removable disk drive, a hard disk drive, a direct access storage device (DASD), an optical drive e.g., a CD drive, a DVD drive, etc., and/or a tape drive, among others. Furthermore, computer  30  may include an interface with one or more networks  38 , e.g., a LAN, a WAN, a wireless network, and/or the Internet, among others, to permit the communication of information with other computers coupled to the network. It should be appreciated that computer  30  typically includes suitable analog and/or digital interfaces between processor  31  and each of components  32 ,  33 ,  34 ,  36  and  38 , as is well known in the art.  
         [0033]    Computer  30  operates under the control of an operating system  40 , and executes various computer software applications, components, programs, objects, modules, etc., such as an executable program  42 , a calling stack  44 , a debugger  50 , among others. The debugger software application  50  is resident in memory  32  for the purpose of debugging one or more executable computer programs, e.g., executable program  42 . A calling stack  44  associated with executable program  42  is utilized by operating system  40  during the execution of program  42 . These and other various applications, components, programs, objects, modules, etc. may also execute on one or more processors in another computer coupled to computer  30  via a network  38 , e.g., in a distributed or client-server computing environment, whereby the processing required to implement the functions of a computer program may be allocated to multiple computers over a network.  
         [0034]    In general, the routines executed to implement the embodiments of the invention, whether implemented as part of an operating system or a specific application, component, program, object, module or sequence of instructions will be referred to herein as computer programs or simply programs. The computer programs typically comprise one or more instructions that are resident at various times in various memory and storage devices in a computer, and that, when read and executed by one or more processors in a computer, cause that computer to perform the steps necessary to execute steps or elements embodying the various aspects of the invention.  
         [0035]    While the invention has and hereinafter will be described in the context of fully functioning computers and computer systems, those skilled in the art will appreciate that the various embodiments of the invention are capable of being distributed as a program product in a variety of forms, and that the invention applies equally regardless of the particular type of signal bearing media used to actually carry out the distribution. Examples of signal bearing media include but are not limited to recordable type media such as volatile and non-volatile memory devices, floppy and other removable disks, hard disk drives, optical disks, e.g., CD-ROM&#39;s, DVD&#39;s, etc., among others, and transmission type media such as digital and analog communication links. In addition, various programs described hereinafter may be identified based upon the application for which they are implemented in a specific embodiment of the invention. However, it should be appreciated that any particular program nomenclature that follows is used merely for convenience, and thus the invention should not be limited to use solely in any specific application identified and/or implied by such nomenclature. The exemplary environments illustrated in FIGS. 1 and 2 are not intended to limit the present invention. Indeed, those skilled in the art will recognize that other alternative hardware and/or software environments may be used without departing from the scope of the invention.  
         [0036]    Routines, often referred to as methods, procedures, and functions, are typically sequences of instructions or statements in a computer program that may be invoked to perform predetermined operations on a computer. The calling history for a computer program is typically maintained by an operating system using a data structure such as a calling stack that maintains information regarding the sequence of routines that are called during the execution of the computer program. A calling stack is a first in-first out (FIFO) data structure. In response to a routine call from a first routine to a second routine, an operating system will generally “push” onto the top of the calling stack an entry that identifies both the first routine, as well as the specific instruction or statement in that routine from which the routine call was made or, alternatively, the instruction or statement in that routine to which control should be returned upon completion of the second routine. The second routine is then executed, and if that routine calls an additional routine, an entry relating to that routine call is also added to the stack. As routines terminate in execution, entries from the calling stack are then “popped” from the top of the stack and the information therein analyzed to determine the routine and instruction therein where control should be returned.  
         [0037]    In accordance with features of the invention, as will be described, greater freedom and flexibility is granted to the computer programmer so she/he can create, use, and store debug scenarios to recognize additional breakpoints and monitored variables, which can be further suggested to the user. Similar to programs that look at the first few characters typed in a word and automatically try to complete the word, in accordance with features of the invention, the algorithm considers the current scenario of a breakpoint and compares it to past scenarios which have been stored. If the similarity between the current scenario and a previously stored scenario exceeds a user-defined threshold, the debugger quickly and efficiently locates and restores settings such as breakpoints and monitored variables. This process thus saves the user significant time when establishing these parameters in a new program and further reduces debug time by ensuring the user has not forgotten that critical breakpoint.  
         [0038]    The invention further recognizes and saves debug scenarios associated with the various source code units in a database. It tracks the breakpoints, step locations, and states of variables each time a user debugs a program and then implements a weighting algorithm to determine if the current debug scenario is a commonplace occurrence or is a new phenomena. When the user enters a debug session and adds programs to debug, and adds breakpoints to the programs, the debugger in accordance with features of the invention looks at scenarios to determine which ones best match and, at the user&#39;s request, displays information relating to the best matching scenarios. The user then may select one of them to assist in the current debug session. Once the user selects one of the previously stored matching scenarios, all breakpoints and monitored program variables for the scenario may be restored, as in Canadian patent application serial number 2,347,647 entitled  Storing and Restoring Snapshots of a Computer Process  by Vadim Berestetsky, Cary Bates, Paul Day, and John Santosuosso, filed May 15, 2001, which is hereby incorporated by reference it its entirety.  
         [0039]    To understand how the matching of debug scenarios may be accomplished, consider FIG. 3. FIG. 3 is an example of graphical user interface that can be used to determine the factors that might comprise the scenario of interest. Given a debug program interrupted at a breakpoint, a scenario may comprise, for example, breakpoints, step locations, monitored and changed variables, and set variables including their values and locations and step locations. This inclusion of what comprises a scenario is not intended to be limitative, but only illustrative. One of ordinary skill in the art will realize that certain parameters are unique or of more or less interest in particular programs. In an integrated development environment (IDE), for instance, macro variables or changed source code may be other variables tracked during a debug session.  
         [0040]    Each of the parameters comprising a defined scenario, moreover, may contribute a different weight to a total match score depending upon the debug program, the program undergoing debugging, the previously stored scenarios, etc. For example, a common object call or other program statement stepped through in many scenarios may contribute less weight to an overall comparison between two scenarios than if a breakpoint is set on the same line in both scenarios. Similarly, setting a variable to the same value at approximately the same location in the program would also contribute more weight than simply monitoring the variable. It should be understood that the actual value of these weights is not critical and the algorithm can be tuned by the user or debugger provided. Given this background, the reader is directed to FIG. 3 which illustrates how a user can set three parameters to be compared in two programs undergoing debugging. The first line  310  represents the scenario frequency  314 , i.e., how many times the scenario is found to match in a period of time. If the user wishes to assign a higher score to a scenario that is a more common occurrence in a program undergoing debugging, the tab  312  may be slid further to the right using a mouse or other visual input device. In addition, scenario recency represents how recently the scenario was used. Recently used and heavily used scenarios may initially be given a smaller score by sliding tab  316  to the left because these scenarios may be very common scenarios like certain object calls or, on the other hand, a higher score may be assigned by sliding tab  316  to the right because the scenario may have a slight advantage in that these are more likely to be the ones that the user wants.  
         [0041]    A second parameter may be the breakpoint proximity  320 . If the breakpoint in the program undergoing debugging is near/far to the breakpoint in the saved scenario, the proximity may be given a higher weight by sliding tab  322  to the right. Similarly, even if a breakpoint is not set at the same location some weight would be given if the breakpoint is set close to the original location. The closer the breakpoints is to the original location, the more weight the breakpoint proximity would be given toward the total matching score. The further away, the less weight would be given. Again, distance of a program statement or a line to a breakpoint is an adjustable parameter that could be configured via the proximity coefficient  324  but the weighting value would most likely erode, perhaps even exponentially, as the distance increases, and the user may define that if the breakpoints are more than five lines apart little or no weight would be given towards the total match score. Another parameter that may be watched and compared during a debug session is a monitored expression  330 . Broadly, a monitored expression is a computer language expression and the location at which the expression is evaluated. If the monitored expression is in a similar location as in a stored scenario, that proximity can be set by sliding tab  332 . The weighting factor  324  of the monitor proximity coefficient can also be set in box  334 . Thus, matching up breakpoints and variables monitored as described above may be the primary contributor to the match score, other parameters may be set with smaller weighting factors.  
         [0042]    [0042]FIG. 4 is an illustration of a graphical user interface that may appear during a debug session implementing features of the invention. While the user interface shown in this and all other examples of user interfaces is a graphical one capable of display on a computer monitor or a flat panel display, etc. it is fully intended that the user interfaces disclosed herein may cover any visual, audible, or tactile method and device with which to communicate and interact with a user. A screen  400  is displayed having a toolbars  410  and  412  representative of the operating system and the debug program, respectively. The program undergoing debug is set forth in the tab  414  of the larger window  420  encompassing three smaller windows  422 ,  424 , and  426 . Window  426  shows the actual lines of code of the program undergoing debugging. Window  422  has two tabs labeled Breakpoints and Programs of which the Breakpoints is selected by the darkened circle  430 , and as can be seen in window  426 , the breakpoint at line  117  is highlighted. Window  424  illustrates has two tabs: Monitors and Locals of which Monitors is selected. The state of variable “player1”  440  is selected to indicate is the monitored expression in this case, i.e., perhaps every time a breakpoint occurs, the value of “player1” will be evaluated. Locals displays the local variables that may be scoped locally to a procedure, such as in JAVA or C++.  
         [0043]    In accordance with features of the invention, the state of the variables of window  424  at the breakpoints shown in window  422  are monitored through the program instructions shown in window  426  as the program undergoes debugging. These parameters are given weighting factors as described with respect to FIG. 3 and are compared against existing scenarios. If the current scenario as shown in FIG. 4 is found to be so dissimilar as to be below a threshold value to any existing scenario then a new scenario is created.  
         [0044]    In comparing two debug sessions for similar scenarios a total possible matching score is computed and compared to an actual score. If the actual score is some threshold percentage of the total possible score, say for example, 75%, then the preexisting stored scenario is said to match the current scenario. At this point if desired the user should be able to bring up a window that will list and explain all matching scenarios. For example, clicking on an appropriate toolbar button in the debug program may invoke list of matching scenarios and their complete descriptions. In the case that more than one stored scenario matches the current scenario by more than the threshold percentage, the previously stored scenario that has the best match to the scenario undergoing debug may be selected. Such a listing of matching scenarios is presented in an illustration of a graphical user interface  500  as shown in FIG. 5. Window  510  lists each preexisting scenario which may have a simple name  512  and a more descriptive alias  514 . The matching score  516  may also be displayed. When displayed to the user the scenarios could be ordered by highest score. Scenarios with a matching score of zero or below a threshold or other matching value need not be listed.  
         [0045]    In order to help the user choose a particular scenario, the user interface  500  of FIG. 5 will point out which scenario attributes match the actions taken by the user so far. Each scenario might be saved as a file in the directory where user&#39;s profiles reside. For a previously stored scenario highlighted in window  510 , C:\WINNT\PROFILES\MYPROFILE\DbgProfScenario1, the attributes may be shown in window  520 . For example, window  520  has the step locations  522  shown but a user may also be able to consider the breakpoints or the monitors of the previously stored scenario by selected the appropriate tab  524  and  526 , respectively. Details of the step locations may be additionally displayed, e.g., the module of the compiled code, a function within the module, the line number and step type within the function, etc. One of skill in the art will realize that other details may be displayed depending, of course, on the debug program, the program undergoing debugging, the objects involved, etc.  
         [0046]    Window  530  of FIG. 5 provides a means by which the user can access all recorded attributes of the current scenario. Window  530  has three tabs indicating the user may access each step location  532 , each breakpoint  534 , and each monitored variable  536  of the attributes of the debugged program. In this fashion, the attributes of the debugged program corresponding to the matching scenarios may be displayed to the user.  
         [0047]    [0047]FIG. 6 is an example of a data structure that can be used to store the matching scenarios. The first data structure  610  may comprise a number of scenarios  612 , each of which has a total possible matching score matching in column  614 , the actual score in column  616 , and a list of module records in column  618 . Each module record  620  may have a number of debug entity records  630 , each of which provide details of which may be displayed in the user interface of FIG. 5.  
         [0048]    In fact, FIG. 7 provides more details of the data structure of debug entity records  630  which may include the breakpoint record  710  recording the location of the breakpoint in the matched scenario. The matched flag of the each breakpoint indicates whether the breakpoint of the previously stored scenario matches the current scenario. This is a convenient technique to avoid scoring the same debug entity more than once during a session. The step record  720  may indicate the location of the step function and the matched flag. The monitored variable record  730  could contain the name of the variable, the location, e.g., either the line number or the memory location, and the matched flag of the variables. If the variable changes, moreover, the changed variable record  740  could contain location and the value of the changed variable.  
         [0049]    The process by which a debug program can implement features of the invention begins with the flow chart of FIG. 8. At step  810 , the process starts and the first inquiry at step  812  is whether a debug operation is to be performed on a program. If the response is yes, then for each element in the scenario list at step  820 , normal debug processing occurs at step  814 , meaning that the breakpoints are set, the steps are monitored, it is determined if the program undergoing debugging matches any preexisting scenarios and then the operation is performed. For each debug entity record  630 , step  824 , of each module record  620 , step  822 , in each scenario  612 , step  820 , the process determines if there is a match to the current program undergoing debugging, as in step  830 . If the match score is greater than some threshold value or percentage, then at step  832 , the match score is added to column  616  of FIG. 6.  
         [0050]    If, however, a debug operation is not performed at step  812 , then the process inquires at step  830 , if the task is to restore a scenario. If the answer is yes, then the scenario list  610  may be sorted by score in step  832  and may be displayed in step  834 . If the user or the program then selects a scenario as matching in step  840 , the process then restores the scenario in step  842 . If, however, either the user does not wish to restore a scenario at step  830  or a scenario is not selected at step  840 , the process is continued onto the flow chart of FIG. 9.  
         [0051]    [0051]FIG. 9 shows additional steps from a debug process incorporating features of the invention. At step  830  and/or at step  840  from FIG. 8 wherein the user has decided he/she does not wish to restore or select a scenario, the process begins at step  910  for each of the scenarios listed in the data structure  610  of FIG. 6, and determines in step  920  if the score is above or equal to some predetermined threshold percentage of the total score. If so, then an indicator is turned on in step  922 . An indicator may be, for instance, a toolbar button changing from green to yellow or red depending on the percentage of the match in the user interface of FIG. 5 or a scenario being highlighted, etc. If, however, the user does not wish to match any scenario, then in step  930 , the process inquires whether the user wishes to exit the debug program. If not, the process returns to step  812  of FIG. 8. If, however, the user does wish to exit the debug operation in step  930 , the process checks in step  940  to see if an indicator is on meaning that a preexisting scenario has been found to have a matched percentage greater than or equal to the threshold, and the program exits. If, however, the indicator is not on, it means that there is no scenario that matches as well as or better than the current scenario and the current scenario in the debugging program is saved in step  942  as a new scenario. The process then computes and saves the total possible matching score, by, for example, assuming that everything matches and totaling the individual matches.  
         [0052]    [0052]FIG. 10 illustrates the possible process flow of determining if a previously stored scenario listed in the data structure  610  of FIG. 6 matches the current scenario of the program undergoing debugging. In step  1000 , the process begins and determines if the match flag is equal to TRUE in step  1010 . If the match flag is equal to TRUE, then in step  1020 , the user is asked if he/she wishes to step through the record of scenarios that match. If so, then in step  1022 , the process inquires if the current operation is a step operation. If so, then in step  1026 , the process determines if the absolute value of the distance between the step location and the current value location is less than some step match value, in other words, are the locations close enough in proximity to match? If yes, then in step  1028 , the match flag is set to TRUE, and the match score for the step match is calculated using the distance and the weighting factor allocated to the step record function.  
         [0053]    If the step record does not match, then in step  1040 , the breakpoint record is examined. In step  1042 , the process queries if the current operation is a breakpoint operation. If so, then in step  1044 , the process determines if the absolute value of the location of the breakpoint less the current location is less than some breakpoint match value. If so, then the match flag is assigned as true in step  1028  and the match score is calculated using the weighting factor to match the break amount in step  1048 . The process returns in step  1032 .  
         [0054]    A similar process for each record monitor begins in step  1050 . If the monitor records are to be evaluated, then in step  1052 , the process asks if the monitored variable is the same variable as in the stored scenario? If so, then the match flag is assigned to be TRUE as in step  1028  and the weighting factor ascribed to the variable is considered and the variable match is calculated and added to the score. The process then asks if the variable has changed in the record in step  1060 . If so, then the process continues to step  1100  of FIG. 11.  
         [0055]    In FIG. 11, the process begins in step  1100  and asks if the current operation is one to change the value of a variable. If so, then, in step  1120 , the process determines if the absolute value of the variable&#39;s location from the entity record less the current location of variable is less than a predetermined amount. If yes, then in step  1130 , the process checks if the values of the variable is the same as the variable&#39;s value in the stored scenario. If so, then the match flag is set to TRUE in step  1028 , and match score is updated in step  1132  and process returns in step  1032  to step  830 . In this fashion, the user can compare the breakpoints, the operations, and the variables to determine if there are similar scenarios. One, of course, realizes that parameters other than or in addition to the breakpoints, operations, monitored expressions may be used to compare scenarios. These parameters are intended to be merely illustrative and not limitative.  
         [0056]    After having executed a number of instructions and having set some basic breakpoints, the user can request the debugger to recall previously stored scenarios matching the current scenario undergoing debugging. The recalled scenarios may be displayed best match first.  
         [0057]    Even if the user has not requested that previously stored scenarios be listed, the debugger incorporating features of the invention may remind the user a closely-related or near-matching scenario that was previously stored exists. Once the process described herein matches at least one scenario having matching scores within the threshold range for a match based on the breakpoints, steps, and monitored variables entered so far,  
         [0058]    The rest of the scenario attributes will also be indicated to the user. As a matter of fact, by pressing a “Set” button, the user could actually add those attributes to the current debug session. Of course, they may be indicated as Inactive by a different color or otherwise setting off the inactive breakpoints and monitors from the for the active ones.  
         [0059]    In the debug environment program modifications do occur. Normally when a program is modified in this environment, a few lines of code are either inserted, deleted, or changed. One method to overcome minor changes to the program is to compute a cyclic redundancy coded (CRC) or a value for each event in the scenario that refers to a line of code. These events can include breakpoint locations and steps. If the line that a breakpoint was set at is not the same line, i.e., the CRC does not match, then the invention can see if by moving up or down a few lines, it can find the line with the matching CRC and adjust the scenario for the modified program. Cooperating source editors can also be used to identify where lines have been inserted or changed so debug scenarios can be maintained.  
         [0060]    If, however, no preexisting scenarios match within the threshold value or some other value, the user may be asked if he/she wishes to store the scenario of the program undergoing debugging as a new scenario? If the answer is yes, the scenario of the current debugged program will be stored.  
         [0061]    While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example and not limitation and that variations are possible. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.