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Subject: Re: [Boost-build] [python] Python build description
From: Stefan Seefeld (seefeld_at_[hidden])
Date: 2010-07-20 12:55:48

On 07/20/2010 12:09 PM, Vladimir Prus wrote:
> On Wednesday 14 July 2010 21:33:26 Stefan Seefeld wrote:
>> * do variable dependencies necessarily form a directed acyclic graph, or
>> could they be cyclic ?
> I might be missing something, but what are "variable dependencies". Do you
> mean the fact that make has some scary rules about how variables are evaluated?

Yes, exactly.

> In that case, Boost.Build does not have a matching mechanism, so we don't
> have a problem to solve ;-)

Great. :-)

Though I'm not sure whether this won't come up again at some point.
After all, there was a real need that GNU make addressed.

I can think of situations where the value of a variable depends on
intermediate build steps, such as generated files, so it's hard to
define such variables upfront. Perhaps there are more elegant and
pythonic ways to achieve this, such as target-dependent functions (or
even lambdas) that yield variable values only at particular points
during the execution. Then it is important to make sure there are
well-defined semantics for variable scopes (both, for who can see those
variables and when, as well as what the context in which those variables
become defined can see.


       ...ich hab' noch einen Koffer in Berlin...

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