Last update: 02 June,2000
2000 #005 _____________________________________________________________________________ Topic: OK return values Relevant Sections: tgetent, tgetflag, tgetnum Spec: X/Open Curses Issue 4 Version 2 Resolution Request: ------------------- References in document (e.g. page, clause, figure, and/or table numbers or URL if applicable): http://www.opengroup.org/onlinepubs/007908799/xcurses/tgetent.html Nature of defect (complete, concise explanation of the perceived problem): Historical practice is that tgetent() returns -1 if the terminfo/termcap database is not found, 0 if the terminal name is not found, and 1 if successful. tgetflag() returns 1 if the capability is present, otherwise 0. tgetnum() returns the numerical value if found, otherwise -1. Almost all current UNIX systems follow this historical practice (despite what their manual pages say). The specification says these functions return OK if successful, otherwise ERR. Most UNIX systems define OK as 0 in term.h/curses.h, and define ERR as -1. An application which calls tgetent() and checks that it returns OK will fail on most systems. If an implementation is changed to conform to the specification, existing applications which call tgetent() and check that it returns 1 will fail, and tgetnum() will be almost useless. (Since these functions are only provided as a "conversion aid", applications which call them will have been written expecting the historical practice.) Solution proposed by the submitter (optional): (in order of decreasing preference) Change all return values to match historical practice. OR Change return values of tgetflag() and tgetnum() to match historical practice, and make the return value of tgetent() implementation-defined. OR Withdraw the functions. (This would allow implementations to keep their existing behaviour. The implementations would then be standard conforming and existing applications would keep on working.) Resolution Response ------------------- For this revision of the specification conforming implementations may either provide the behavior as currently specified by XCurses, Issue 4, Version 2 or the historical behavior as described the "Nature of defect" section above. In a future revision since these functions are marked To Be Withdrawn, they will be withdrawn. Rationale ------------- This is an agreed problem: The tgetent(), tgetflag(), and tgetnum() can only behave as specified if the value of the termcap entry for name is OK, the Boolean value of an id being looked up by tgetflag() matches the value of OK, or the numeric value of an id being looked up by tgetnum() is OK. Circulated for review: 27 May 2000 Proposed resolution: 27 May 2000