Re: [HACKERS] elog with automatic file, line, and function
Peter Eisentraut <[EMAIL PROTECTED]> writes: > Tom Lane writes: >> #define ELOG(ARGS) (elog_setloc(__FILE__, __LINE__), elog ARGS) > Would the first function save the data in global variables? Yes, that's what I was envisioning. Not a super clean solution, but workable, and better than requiring varargs macros. regards, tom lane ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] elog with automatic file, line, and function
Tom Lane writes: > Sure it is, it just requires a marginal increase in ugliness, namely > double parentheses: > > ELOG((level, format, arg1, arg2, ...)) > > which might work like > > #define ELOG(ARGS) (elog_setloc(__FILE__, __LINE__), elog ARGS) Would the first function save the data in global variables? -- Peter Eisentraut [EMAIL PROTECTED] http://yi.org/peter-e/ ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl
Re: [HACKERS] elog with automatic file, line, and function
Peter Eisentraut wrote:
>
> It has been brought up that elog should be able to automatically fill in
> the file, line, and perhaps the function name where it's called, to avoid
> having to prefix each message with the function name by hand, which is
> quite ugly.
>
> This is doable, but it requires a C preprocessor that can handle varargs
> macros. Since this is required by C99 and has been available in GCC for a
> while, it *might* be okay to rely on this.
>
> Additionally, C99 (and GCC for a while) would allow filling in the
> function name automatically.
>
> Since these would be mostly developer features, how do people feel about
> relying on modern tools for implementing these? The bottom line seems to
> be that without these tools it would simply not be possible.
It is possible, however, the macros require an extra set of parentheses:
void elog_internal(const char* file, unsigned long line, ... );
#define ELOG(args) elog_internal(__FILE__, __LINE__, args)
ELOG(("%s error", string))
For portability to older compilers, you should probably not require C99.
Also, I'm not positive, but I think that varargs are not part of C++
yet.
However, they will likely be added (if not already in draft form).
Neal
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Re: [HACKERS] elog with automatic file, line, and function
* Tom Lane <[EMAIL PROTECTED]> [010319 18:58]: > Ian Lance Taylor <[EMAIL PROTECTED]> writes: > > Tom Lane <[EMAIL PROTECTED]> writes: > >> BTW, how does that work exactly? I assume it can't be a macro ... > > > It's a macro just like __FILE__ and __LINE__ are macros. > > > gcc has supported __FUNCTION__ and __PRETTY_FUNCTION__ for a long time > > (the latter is the demangled version of the function name when using > > C++). > > Now that I know the name, I can find it in the gcc docs, which clearly > explain that these names are not macros ;-). The preprocessor would > have a tough time making such a substitution. > > However, if the C99 spec has such a concept, they didn't use that name > for it ... My C99 compiler (SCO, UDK FS 7.1.1b), defines the following: Predefined names The following identifiers are predefined as object-like macros: __LINE__ The current line number as a decimal constant. __FILE__ A string literal representing the name of the file being compiled. __DATE__ The date of compilation as a string literal in the form ``Mmm dd .'' __TIME__ The time of compilation, as a string literal in the form ``hh:mm:ss.'' __STDC__ The constant 1 under compilation mode -Xc, otherwise 0. __USLC__ A positive integer constant; its definition signifies a USL C compilation system. Nothing for function that I can find. LER > > regards, tom lane > > ---(end of broadcast)--- > TIP 3: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to [EMAIL PROTECTED] so that your > message can get through to the mailing list cleanly -- Larry Rosenman http://www.lerctr.org/~ler Phone: +1 972-414-9812 E-Mail: [EMAIL PROTECTED] US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749 ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl
Re: [HACKERS] elog with automatic file, line, and function
Ian Lance Taylor <[EMAIL PROTECTED]> writes: > Tom Lane <[EMAIL PROTECTED]> writes: >> BTW, how does that work exactly? I assume it can't be a macro ... > It's a macro just like __FILE__ and __LINE__ are macros. > gcc has supported __FUNCTION__ and __PRETTY_FUNCTION__ for a long time > (the latter is the demangled version of the function name when using > C++). Now that I know the name, I can find it in the gcc docs, which clearly explain that these names are not macros ;-). The preprocessor would have a tough time making such a substitution. However, if the C99 spec has such a concept, they didn't use that name for it ... regards, tom lane ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] elog with automatic file, line, and function
Tom Lane <[EMAIL PROTECTED]> writes: > > Additionally, C99 (and GCC for a while) would allow filling in the > > function name automatically. > > We could probably treat the function name as something that's optionally > added to the file/line error report info if the compiler supports it. > > BTW, how does that work exactly? I assume it can't be a macro ... It's a macro just like __FILE__ and __LINE__ are macros. gcc has supported __FUNCTION__ and __PRETTY_FUNCTION__ for a long time (the latter is the demangled version of the function name when using C++). Ian ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [HACKERS] elog with automatic file, line, and function
Peter Eisentraut <[EMAIL PROTECTED]> writes: > It has been brought up that elog should be able to automatically fill in > the file, line, and perhaps the function name where it's called, to avoid > having to prefix each message with the function name by hand, which is > quite ugly. > Since these would be mostly developer features, how do people feel about > relying on modern tools for implementing these? Not happy. A primary reason for wanting the exact location is to make bug reports more specific. If Joe User's copy of Postgres doesn't report error location then it doesn't help me much that my copy does (if I could reproduce the reported failure, then gdb will tell me where the elog call is...). In particular, we *cannot* remove the habit of mentioning the reporting routine name in the message text unless there is an adequate substitute in all builds. > The bottom line seems to be that without these tools it would simply > not be possible. Sure it is, it just requires a marginal increase in ugliness, namely double parentheses: ELOG((level, format, arg1, arg2, ...)) which might work like #define ELOG(ARGS) (elog_setloc(__FILE__, __LINE__), elog ARGS) > Additionally, C99 (and GCC for a while) would allow filling in the > function name automatically. We could probably treat the function name as something that's optionally added to the file/line error report info if the compiler supports it. BTW, how does that work exactly? I assume it can't be a macro ... regards, tom lane ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
[HACKERS] elog with automatic file, line, and function
It has been brought up that elog should be able to automatically fill in the file, line, and perhaps the function name where it's called, to avoid having to prefix each message with the function name by hand, which is quite ugly. This is doable, but it requires a C preprocessor that can handle varargs macros. Since this is required by C99 and has been available in GCC for a while, it *might* be okay to rely on this. Additionally, C99 (and GCC for a while) would allow filling in the function name automatically. Since these would be mostly developer features, how do people feel about relying on modern tools for implementing these? The bottom line seems to be that without these tools it would simply not be possible. -- Peter Eisentraut [EMAIL PROTECTED] http://yi.org/peter-e/ ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
