Allow formula to specify directories that must be directories and not symlink during link step

[adamv]

SDL gets its headers linked to /usr/local/include/SDL.
The SDL_mixer project wants to add a single include /usr/local/include/SDL/SDL_mixer.h

If you install SDL and then SDL_mixer, the latter's symlink will override SDL's symlink, so your include/SDL folder will ONLY have the mixer include.

There are a few ways to handle this:

• Bake the SDL_mixer install into SDL (may not be so bad)
• Use a custom path for SDL_mixer, and then fix up dependent formulas to know about it (ugh)
• Add new infrastructure to support this (design decisions needed there)

[adamv]

I routed around this like so:

http://github.com/adamv/homebrew/commit/5a4fca42057895823b5c244fb7ddd68421b70d7a

Feel free to close this bug, though if you like the approach I used in that formula, I can document it on the wiki.

[mxcl]

Indeed this is a case when we need to allow the formula to interact with the linking behaviour. Should be doable.

[mxcl]

Actually the better solution here perhaps is that when linking, if the directory is already linked to another formula, remove the link, link in all the files inside that dir and continue.

[sophiebits]

Is there a reason why we can't just recreate the entire directory structure and just symlink the individual files? Seems like it would be more consistent, but possibly a bit more messy.

[mxcl]

Well I decided way back to symlink dirs if possible to save on the number of symlinks you have to create.

Eg with boost, symlinking the include/boost directory rather than everything in that directory saves over 3000 symlinks.

[mxcl]

Almost finished this patch.

[mxcl]

Allow multiple formula to symlink the same directory

During the link step, if the destination symlink already exists, unlink it, and create a directory instead, then relink the original contents. Then continue linking the formula in question.

Closed by 5c54f57