[Nix-dev] A standard function to handle deps

[Evgeny Egorochkin]

Sorry for replying late...

On Wednesday 23 June 2010 19:40:18 Marc Weber wrote:
> > I did indeed miss the fact that you can pass var=null and that asserts
> > only for optional vars aren't enough.
> > 
> > So how about adding a "nullGuard" to stdenv.mkDerivation? It isn't going
> > to affect a single working package but would help to catch errors early.
> 
> I'd like to wait until more people reply to this. I didn't encounter
> such a case yet. So it may or may not help. In fact passing null could
> be convenient in some cases eg for testing

I can't come up with such a case. Examples?

> Have you been hurt by a missing nullGuard function?

It is a reasonable safety check. The purpose is to fail due to assert if you 
have missing required dependencies, instead of having ./configure fail.

Can you live without it? Yes of course, but it's a cleaner solution.

-- 
Evgeny