Editor is a simple class that provides a multiline text field bundled with a pop-up menu system and a search and replace facility.
Inheritance is an important object-oriented technique.
For this reason, the X toolkit designers had to resort to inheritance by convention. Specifically, to create a new X toolkit-based widget we must create various data structures that hold the necessary state information and connect these data structures to the superclass data structures by pointer fields. The Editor Class Figure 1 shows the original CRC design card for Editor from the November column, which has a user-oriented list of responsibilities. StreamDB is no longer a collaborator because in our January column we provided xrolo.db.c , a linking module that handles the transfer of text between entries in the stream database and the viewport. Its actual implementation is given in the xrolodex source code and is left as an exercise for the curious reader.