I want to suggest a different way of handling constants.py and config.py the current way is clumsy and makes making convoluted code easy.
GLOBAL VARIABLES ARE BAD. It's not something I invented. It's well accepted that proper scoping yields better code.
The way we use those two files shows how much of a mess globally accessible variable can be.
Not putting paths to executable in constants.py ----------------------------------------------- Instead we should have a module for each utility executable. The module should wrap the utility with a pythonic interface. That way there is no reason for more then one module to have access to a utility's path.
For example:
cat.py ------
_CAT_PATH = @CAT_PATH@
def cat(files): cmd = [_CAT_PATH] + files out, err = exec(cmd) return out
Now there is no need to know where cat is. You have a proper interface to use. Preventing people from re-wrapping the utility over and over. This in turn means you have a canonical wrapper that is more likely to work.
Every other constant -------------------- Other constants should be moved to their proper modules and used only when importing the module makes sense this will give you another step where you make sure your decencies are correct.
Configuration -------------
Configuration files are just parameters to the program. They should be treated as such. Their scope should not leave the main class of the project. In our case VDSM is actually 2 projects meshed together like Siamese twins so I think clientIf.py and hsm.py should be the only ones with access to the config. Everything else should expect to get those values in a regular programmatic fashion.
In my opinion these changes will make VDSM a lot more flexible, will make more parts independent and easily separated and at that end help us make VDSM better for generations to come.
You can help! -------------
* Start by taking you favorite utility and write a proper safe module around it. * When writing new code try and not access the configuration directly. * Modules are free (really) don't just put stuff in misc\utils try and put some order to things.