mxcl/homebrew — pull request #12335 by fish2000 (2012-05-20 17:10:08+00:00)
Title: CImg version 1.5.0-beta, and flexible dependency checking for the phash formula

Added --devel option to CImg to install version 1.5.0-beta, and tweaked the phash formula to work properly when this option is used.

The motivation, in this case, was compiling successfully against CImg using clang (which isn't possible with version 1.4.9 -- you could get phash in there with `--use-llvm`, but doing that created other problems, e.g. you couldn't link the resultant dylibs from a beclanged build python, etc).

*N.B.* The CImg library is implemented as header files; the API is exposed by doing `#include ` which doesn't allow for a clean way of installing multiple parallel versions. That is why the changes to the phash formula eschew `depends_on 'cimg'` in favor of a manual check via the formula factory -- because the devel version is different than the main formula version, it doesn't appear to be installed if the phash formula checks it out with `depends_on`, and Homebrew fails while trying to superfluously repeat the CImg install.