Abstract:
The invention includes computer instructions that operate to generate a failure indication upon encountering a failure during an operation performed for a user design. The instructions further operate to automatically facilitate a user in determining a solution for the failure. As a result, the invention provides improved error reporting and recovery.

Description:
RELATED APPLICATIONS 
     This application is a continuation of Application Ser. No. 09/199,990, titled “ERROR HANDLING AND REPRESENTATION IN A COMPUTER-AIDED DESIGN ENVIRONMENT”, filed on November 24, 1998, now U.S. Pat. No. 6,363,503. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to computer-aided design tools. More specifically, the present invention relates to processing and representation of error messages within a computer-aided design environment. 
     BACKGROUND OF THE INVENTION 
     Traditionally, one of the weakest and most overlooked areas of software design and development is error reporting and recovery. Prior art computer-aided design systems typically provide multiple error and/or warning messages as the result of a single fault. Multiple messages result from architectural structures wherein warning/error messages are passed through multiple architectural levels from the level where the fault occurs to the level where the warning/error messages are presented to the user. 
       FIG. 1  is a conceptual illustration of prior art of function calls and returns. For purposes of explanation, it is assumed that the second function called in the example of  FIG. 1  cannot complete execution by performing the desired functionality. 
     According to typical prior art computer aided design applications function(A)  100  calls function(B)  120  with first function call  110 . First function call  110  can be any type of function call known in the art, for example, function calls according to a C++ programming environment, or a C programming environment. 
     Instructions of function(B)  120  are executed until an instruction that calls function(C)  140  is executed. As a result, function call  130  is executed. Instructions of function(C)  140  are executed until some instruction cannot be executed properly. For example, an instruction may perform the function of opening a non-existent file, or a divide by zero operation, a constraint solver failure, etc. 
     When execution of instructions in function(C)  140  stops because an instruction cannot be complete, function(C)  140  returns a result to function(B)  120  via return  150 . Return of results can be performed by any manner known in the art. Typically, when function(C)  140  cannot complete execution, the result(s) returned indicate that an error occurred, and the possible cause of the software fault. 
     Upon receiving error result(s) from function(C)  140 , function(B)  120  cannot complete execution and similarly returns error results to function(A)  100  via return  160 . Function(A)  100  thus receives two error results caused by a single error. The greater the number of function calls the greater the number of error messages that are generated based on a single error, which can be confusing and overwhelming to a user of a computer aided design tool employing such an error reporting scheme. 
     The multiple error messages often result from a subroutine call that returns a error result to the calling subroutine, which in turn returns its own error result along with the original error message to the corresponding subroutine. This process continues until a routine responsible for error reporting is reached. By that time, multiple error results have been generated for a single fault. The same sequence occurs for warning messages. 
     Another shortcoming of the prior art is that typically only the first or last message for an error is reported, which either lack the context in which the error occurred or lack sufficient detail to accurately describe the error. What is needed is an error reporting mechanism that reduces the number of error/warning messages caused by a single execution fault while providing sufficient detail for the user to understand the error/warning. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation in the figures of the accompanying drawings in which like reference numerals refer to similar elements. 
         FIG. 1  is a conceptual illustration of prior art of function calls and returns. 
         FIG. 2  is a computer system suitable for use with the present invention. 
         FIG. 3  is a conceptual illustration of function calls and returns according to one embodiment of the present invention. 
         FIGS. 4A and 4B  are one embodiment of an error reporting user interface suitable for use with the present invention. 
         FIGS. 5A and 5B  are one embodiment of an error reporting user interface suitable for use with the present invention. 
         FIG. 6  is a computer system providing error/warning reporting according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A method and apparatus for processing and representing error messages within a computer-aided design environment is described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention can be practiced without these specific details In other instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the present invention. 
     As used herein, an “error” (also referred to as a hard failure) is a condition that must be corrected in order to proceed, and a “warning” (also referred to as a soft failure) is a condition that is not required to be corrected in order to proceed; however, the result achieved may be different than the result desired. The present invention allows error/warning information to be stored in a central storage location by the function in which the error/warning causing fault occurs. The function then returns a result indicating that the function did not perform as expected. 
     The calling function does not add an error/warning message of its own when returning, if necessary, to another calling function. The calling function can add detail to the message in order to provide additional detail or context in order to better describe the error/warning. Thus, a minimum set of warning/error messages can be stored and used for reporting the fault that caused the error/warning. In one embodiment, a hierarchical graphical error/warning log provides varying levels of error/warning information in response to user input. 
       FIG. 2  is one embodiment of a computer system suitable for use with the present invention. Computer system  200  includes bus  201  or other communication device for communicating information, and processor  202  coupled to bus  201  for processing information. Computer system  200  further includes random access memory (RAM) or other dynamic storage device  204  (referred to as main memory), coupled to bus  201  for storing information and instructions to be executed by processor  202 . Main memory  204  also can be used for storing temporary variables or other intermediate information during execution of instructions by processor  202 . Computer system  200  also includes read only memory (ROM) and/or other static storage device  206  coupled to bus  201  for storing static information and instructions for processor  202 . Data storage device  207  is coupled to bus  201  for storing information and instructions. 
     Data storage device  207  such as a magnetic disk or optical disc and corresponding drive can be coupled to computer system  200 . Computer system  200  can also be coupled via bus  201  to display device  221 , such as a cathode ray tube (CRT) or liquid crystal display (LCD), for displaying information to a computer user. Alphanumeric input device  222 , including alphanumeric and other keys, is typically coupled to bus  201  for communicating information and command selections to processor  202 . Another type of user input device is cursor control  223 , such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor  202  and for controlling cursor movement on display  221 . 
     One embodiment of the present invention is related to the use of computer system  200  to process and present errors related to computer-aided design tools. According to one embodiment, error processing and presentation is performed by computer system  200  in response to processor  202  executing sequences of instructions contained in memory  204 . Execution of the sequences of instructions contained in memory  204  causes processor  202  to process and present error messages, as will be described hereafter. 
     Instructions are provided to main memory  204  from a storage device, such as magnetic disk, CD-ROM, DVD, via a remote connection (e.g., over a network), etc. In alternative embodiments, hard-wired circuitry can be used in place of or in combination with software instructions to implement the present invention. Thus, the present invention is not limited to any specific combination of hardware circuitry and software instructions. 
       FIG. 3  is a conceptual illustration of function calls and returns according to one embodiment of the present invention. As with the function calls of  FIG. 1 , it is assumed that the second function called in the example of  FIG. 3  cannot complete execution when performing the desired functionality. 
     Function(A)  300  includes sequences of instructions that are executed, for example, by processor  202  of computer system  200 . An instruction in the sequence of instructions causes function(A)  300  to call function(B)  320  via function call  310 . Function calls can be performed in any manner known in the art. 
     Function(B)  320  similarly includes sequences of instructions that are executed until an instruction causes a function call. As a result of the instruction that causes the function call, function(C)  340  is called via function call  330 . Instructions included in second function call  340  are executed until an instruction cannot be executed properly. 
     When an instruction cannot be executed property, error notification is sent to error/warning storage structure  380  by notifier  370 . In one embodiment, notifier  370  is a “thin wrapper” class that is described in greater detail below. Alternatively, notifier  370  can be a sequence of instructions of function(C)  340  or an independent called function (not shown in  FIG. 3 ), which results in higher overhead than the thin wrapper class embodiment. Function(C)  340  returns results to function(B)  320  via  350 . Function(B)  320  in turn returns results to function(A)  300  via  360 . 
     Based on results returned from function(B)  320 , function(A)  300  is notified that at least one error and/or warning occurred and that at least one called function did not successfully complete execution. Function(A)  300  retrieves error results from error/warning storage structure  380 , via  390 , to report the error/warning results to the user of the computer aided design tool. One embodiment for presenting the report is described in greater detail below. 
     Because the present invention provides a central storage structure for error/warning results, only a minimal set errors/warnings are reported to the user. In one embodiment, intermediate called functions (e.g., function(B)  320 ) do not receive full error results as in the prior art and subsequently do not pass the received error results with an additional local error result to the corresponding calling function. Alternatively, intermediate called functions add information to the stored error/warning messages if the information is related to details and/or context of the error/warning, and add nothing otherwise. In other words, the function in which the error occurred reports the error to the error/warning storage structure and intermediate functions add information if that information is helpful in reporting. Thus, the user of the computer aided design tool is presented with a more concise listing of errors that occur during an attempted operation. 
     In one embodiment, the present invention accomplishes the functionality described above by defining an error reporting class referred to herein as the “UTxResult” class. Briefly, a “class” is an object oriented programming construct that describes the characteristics and the operations of the corresponding constituent objects. The following summary is a brief description of classes used in one embodiment of the present invention. Modifications to the specific classes described below can be made without deviating from the spirit and scope of the present invention. 
     In one embodiment, UTxResult includes a 32-bit error code having 2 severity, 12 facility, 16 error, and 2 reserved bits. UTxResult is used by computer aided design tool subsystems to encode informational, warning and error results. A method is provided to map a UTxResult to a string in the subsystem resource file, which is described in greater detail below. Briefly, a text string that is used to report a particular error is stored in the subsystem resource file and retrieved to report errors based on the result returned. In one embodiment, a zero result from a routine indicates successful completion of the routine. A non-zero result indicates unsuccessful completion of the routine and presence of an error and/or warning in the error/warning log. 
     UTxResult is a “thin wrapper” class that is used to report non-zero error codes to the error/warning storage structure. When a non-zero UTxResult is returned from a function, a compiler-generated constructor communicates to the error/warning storage structure that the return code is non-zero. When a zero UTxResult is returned no communication with the error/warning storage structure occurs. 
     A UTxResult object can also be constructed as an automatic (e.g., stack based) instance. In one embodiment, the function that generated the non-successful result is responsible for reporting the result either prior to exit, or via a return value. In one embodiment, functions that have non-trivial implementations should return a UTxResult. Exceptions are if the function is performance sensitive or is guaranteed to succeed. 
     The UTxResult class is a thin wrapper class because, in one embodiment, non-zero integer results are represented by a macro that expands to a constructor call of the type UTxError or UTxWarning. The constructor call results in the construction of a specialized type (e.g., error or warning) UTxResult object that logs an error/warning report with the error/warning storage structure. Because error/warning reporting is separated via a macro from constructor of zero results, overhead for error-free execution is low. 
     In one embodiment, by providing an error/warning storage structure, an error/warning is reported once by the function in which the error/warning occurred and not communicated multiple times in multiple function results. Intermediate results need not determine whether an error/warning message has been stored in the error/warning storage structure. Thus, error/warning reporting is simplified and more precise, which results in improved error/warning recovery. A single error/warning log that stores errors/warnings also provides functionality to simpler and more context-sensitive error/warning reporting environment than would otherwise be possible. 
       FIGS. 4A and 4B  are one embodiment of an error reporting user interface suitable for use with the present invention. While the interface of  FIGS. 4A and 4B  are described in terms of error reporting, the description is equally applicable to warning reporting. 
       FIG. 4A  is an error report summary that can be presented to a user of a computer aided design tool. Report summary  400  includes title bar  405  that indicates an operation that caused the error/warning. Sentence  410  describes an error in general terms. In one embodiment, an icon is presented to provide the user with visual, non-textual feedback. 
     Button  420  (OK) allows the user to dismiss summary  400 . Button  422  (Help) allows the user to request additional information about errors and/or warnings. Button  424  (More) allows the user to obtain additional information about the errors and/or warnings being reported. In one embodiment, selection of button  424  provides the detailed error log window of  FIG. 4B . 
       FIG. 4B  is a detailed error report that can be presented to a user of a computer aided design tool. As with the summary of  FIG. 4A , error log  450  can also be used to present warning information to the user. Title bar  455  indicates an operation that caused the error/warning to occur. 
     Button  470  (OK) allows the user to dismiss log  450 . Button  472  (Help) allows the user to request additional information about errors and/or warnings. Button  474  (Less) allows the user to reduce the amount of information about the errors and/or warnings being reported. In one embodiment, selection of button  474  provides the error summary window of  FIG. 4A . 
     In one embodiment, a list of errors is presented in field  490 . In the example of  FIG. 4B , three errors (labeled  480 ,  482  and  484 ) are presented. Brief descriptions of the associated errors can also be presented. In one embodiment, explanation  460  provides a one sentence description of a selected error. In the example of  FIG. 4B , error  480  is selected. 
     In one embodiment, errors are presented in a hierarchical manner where each level of the display hierarchy provides a level of information related to the associated error. For example, a construction error caused by a shell that is too thick can be initially presented as a “Could not create shell” in field  490  with an error or warning icon (see, for example, error  480 ). In one embodiment, the text string “Could not create shell” is retrieved from the subsystem resource file based on the return value from the function in which the error/warning occurred. If the user expands the construction error, additional information can be provided, for example, “modeling error: shell too thick.” The text string “modeling error: shell too thick” is also obtained from the subsystem resource file. This additional information provides the user with information about how to recover from the error. 
     In one embodiment selection of an error/warning provides visual feedback related to the cause of the error/warning. For example, if an error is caused by a particular portion of a design, that portion of the design is highlighted in the document/design window. Alternatively, the cause of the error/warning can be visually indicated in another manner. In one embodiment, an icon associated with the error/warning is modified (e.g., a light bulb overlays the ordinary error/warning icon) to indicate that visual feedback can be selected by the user. 
       FIGS. 5A and 5B  are one embodiment of an error reporting error user interface suitable for use with the present invention.  FIG. 5A  is one embodiment of basic error reporting interface. Title bar  530  provides the operation that caused the error/warning described. In one embodiment, title bar  530  is the standard Windows® title bar. Windows® is a registered trademark of Microsoft, Inc. of Redmond Wash. Icon  520  indicates whether an error or warning is described. In one embodiment, an exclamation mark (!) in a triangle is used to represent an error. The plus symbol (+) at the lower portion of icon  520  indicates that additional information is available about the error. Alternatively, other icons can be used. 
     Button  540  allows a user to request help, for example, context sensitive help. Button  550  allows the user to edit the design that caused the error/warning. Button  560  allows the user to accept the error/warning results and proceed. Button  570  allows the user to cancel the error/warning process. 
     Window  500  provides an area in which error/warning reports are displayed. In one embodiment, error/warning reports can be either be basic error/warning summaries or the reports can be more detailed error/warning descriptions. In the embodiment of  FIG. 5A , sentence  510  provides a basic error summary, for example, “Errors found while editing extrusion function.” 
     In one embodiment, selection of icon  520  causes the basic error/warning reporting interface of  FIG. 5A  to be replaced by the detailed error/warning reporting interface of  FIG. 5B . In one embodiment, sentence  510  of  FIG. 5A  is replaced by error/warning description  580  of  FIG. 5B . Error/warning description  580  provides hierarchical information related to the error that occurred as a result of the operation listed in title bar  530 . 
     In one embodiment, the levels of the hierarchy are controlled by user input. For example, the minus signs (−) indicate that a particular level of the hierarchy can be condensed and a plus sign (+) indicates that a particular level of the hierarchy can be expanded. Thus, the user can have control over the amount of information displayed with respect to error/warning descriptions. 
       FIG. 6  is a computer system providing error/warning reporting according to one embodiment of the present invention. Bus  620  provides interconnection between multiple components of computer system  600 . Processor  610  executes sequences of instructions stored in memory  640 . Display device  630  provides an output display when appropriate. 
     Memory  640  stores sequences of instructions for one or more applications. For example, operating system  650  provides an application layer between other applications and the hardware of computer system  600 . Memory  640  also stores computer-aided design (CAD) application  660 . In one embodiment CAD application  660  is Mechanical Desktop® available from Autodesk, Inc. of San Rafael, Calif. However, other applications including other CAD applications and other design related applications can be used with the present invention. 
     Function(A)  662  of CAD application  660  is a function that calls function(B)  664 . Other types of function calls, for example, calls to operating system  650  can also be made. During execution of function(B) an event that causes an error or a warning occurs. An indication of the error/warning is stored in error/warning storage structure  666  as described above. Function(B) returns a result to function(A) indicating that an error/warning occurred and that additional information is stored in error/warning storage structure  666 . 
     Processor  610  continues execution of CAD application  640  as appropriate, which may be to continue execution or to report errors/warnings that have occurred. In reporting of errors/warnings, sequences of instructions in CAD application  660  cause processor  610  display an error/warning report interface on display device  630 . For example, the error/warning summary/log of  FIGS. 4A and 4B  can be used. 
     A user of computer system  600  can use cursor control device  615  to request more or less information related to the error/warning summary or log displayed on display device  630 . Thus, the user has a measure of control over the amount of information displayed regarding one or more errors/warnings that occurred during use of CAD application  660 . 
     In summary, the present invention provides improved error reporting and recovery as compared to that of the prior art. A central error/warning storage structure is used to reduce the number of error/warning messages presented to a user as the result of a single unexpected result. An error/warning reporting interface provides the user with a selectable amount of information as to error/warning recovery options. Thus, the user is provided with a more concise and more effective error/warning recovery options. 
     In the foregoing specification, the present invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.