Way to have git only recognize a file as changed i

In my current project, I am attempting to use git to version control text files that are utilized by software that generates code from them. This in itself isn't a problem, the problem is that every time I generate code, it automatically updates this file with properties such as the date the code was generated, as well as my name.

You can imagine it looking something like this:

SomeHeader{
  -SomeProperty : x
  -NameOfUserThatGenerateCode: myName
  -DateTimeCodeGenerated: 2013-07-23 06:28
  -SomeOtherProperty: y
}

What I want, is a way to tell git to say that "it is okay" if both the Name and CodeGeneration time to change (ie: Ignore that there was a change), but DO care if "SomeProperty" changes to say "z".

In that second case, it would commit the entire file (with the updated autogenerated files).

Is there anyway to do that? I recognize that git does changes at the "file" level, but I am hoping that there might be some sort of pre-processing hook that I can tie into that would only work when git attempts to compare file changes.

For those that care, this will enable me to properly version control rhapsody files.

I would recommend:

keeping a copy of those files (as private files, meaning not versioned): your software would generate code in those copy
a clean script, as a content filter driver, declared in a .gitattributes file (detailed in Git Pro book).

The idea is for that script to detect, on git add:

the content of a 'SomeHeader' property file
if the copy of that file has changed in way you need to keep (in which case you overwrite the versioned file with the content of that copy)
if the copy of that file has not changed significantly, in which case, you don't modify the actual property file.

Note that the "keep a copy" part can be automated also by a content filter driver, with a smudge script activated automatically on git checkout.