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2008.12.18 18:59 "Re: tiffvers.h - TIFFLIB_RELEASE macro addition", by Frank Warmerdam
Bob Friesenhahn wrote: > On Thu, 18 Dec 2008, Frank Warmerdam wrote: >>> >>> The available values are CURRENT, REVISION, and AGE in order of >>> decreasing significance. For example, CURRENT might be 4. >> >> But this is not normally conveniently available to applications building >> against libtiff, right? It requires some sort of configure magic to >> extract the libtool versioning and represent it as macros passed into >> the application. It wouldn't do anything for someone on windows for >> instance. > > Right. That is where the substitution magic which builds tiffvers.h > comes in. Then the versioning info is available to all. It is not > difficult for configure/make to maintain a continually up to date > tiffvers.h. > >>> The approach you describe still only works if the major release >>> update always offers additional features over the previous major >>> release. >> >> I do not understand this comment. > > What I mean is your use of arbitrary libtiff version numbers to > determine if a feature is available. Features can be backported and it > is even possible that a lesser numbered library supports a feature which > is not available in a higher numbered library. Folks, OK, I'm finding interest in TIFFLIB_RELEASE lukewarm at best, and I have decided against going ahead with it. I'll leave things as they are in this regard. For my own purposes I already need to detect whether I have BigTIFF support, so I'll just use TIFFUnsetField() if the date is later than a particular date, and if I have bigtiff support. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent