Putting these both in the same issue since they're related. Two features that have been missing that I've seen in windowmaker and openbox (minus the cached pipes) are these two.
Embedded files approach #1:
<file path="/path/to/extra/file.ext">
This would split the file during the cache process, before officially committing it to the cache. This way, the parse_text() function only deals with the pipes and menu generation. The drawback to this is that if I decide to make a cache retrieval utility to recover file cached contents, it would be altered and thus not represent the file fetched.
Embedded files approach #2:
<pipe command="cat /path/to/file.ext" mode="cache">
This would split the file during the "learning process", where the parse_test() function learns where dynamic pipes are. It will split the file for the cache pipes, get the result, restitch the file, then split it again to learn dynamic pipe locations. The only problem is that this looks kind of sloppy, because this kind of pipe might only be used for menu files. Plus, the algorithm I just wrote looks sloppy
For now, I've decided that it's simpler to just use a cached pipe for this since it won't add as much clutter.