I'm sure this title is fairly obscure. I'm wondering if there is some way in git to tell it that you want a certain file to use different versions of a file when moving between branches, but to overall be .gitignored from the repository.

Here's my scenario: I've got a Flash Builder project (for a Flex app) that I control with git. Flex apps in Flash Builder projects create three files: .actionScriptProperties, .flexProperties, and .project. These files contain lots of local file system references (source folders, output folders, etc.), so naturally we .gitignore them from our repo.

Today, I wanted to use a new library in my project, so I made a separate git branch called lib, removed the old version of the library and put in the new one. Unfortunately, this Flex library information gets stored in one of those three dot files (not sure which offhand). So when I had to switch back to the first branch (master) earlier, I was getting compile errors because master was now linked to the new library (which basically negated why I made lib in the first place).

So I'm wondering if there's any way for me to continue to .gitignore these files (so my other developers don't get them), but tell git that I want it to use some kind of local "branch version" so I can locally use different versions of the files for different branches.