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Re: Hidden dependencies?

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October 1, 2003 03:45
Re: Hidden dependencies?
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I this particular case, it not really a dependency, the docs say

         perldoc -o tk Some::Modulename &

       This is a "plug-in" class that allows Perldoc to use
       Tk::Pod as a formatter class.

       You have to have installed Tk::Pod first, or this class
       won't load.

if you grep, you'll see that the module isn't used or required by
anything. Maybe should be distributed separately with deps on
perldoc and perl-Tk but that sounds a bit drastic.

It's a general problem with packagers and dependencies. Lots of packages
(particularly multimedia players) "require" every single library it can
talk to because that's how it was compiled but it will actually work
perfectly without most of them. Packaging systems don't seem to have any
concept of optionaly requirements (or if they do I've never seen them used).

The "correct" solution is to build a tree (graph?) of dependencies between
modules then start from a list root modules (that is modules which are
designed to be "use"d in public) and traverse the tree to find out what
really is required. cannot be reached from any of these root
modules and so would be an optional requirement.

That requires manintaining a list of publicly usable modules. Perhaps
MakeMaker should have a

public_module => [ 'Use::This', 'Or::This']

then it might even be able to work out PREQREQ_PM by itself (or at least
have a good go at it in non special cases).


Original Message:
From: Johan Vromans
Date: Tue, 30 Sep 2003 21:08:11 +0200
Subject: Re: Hidden dependencies?

Slaven Rezic <> writes:

> Maybe I missed something, but why scanning for perl module dependencies
> at all? Core perl is not supposed to have any perl module prerequisites.

You hit the nail on the head. It is not _supposed_ to have
dependencies. But apparently it _does_ have dependencies, at least
according to some dependency analyzers.

Not scanning this particular kit hides the symptoms, but doesn't cure
the problem (oistrich approach).

I agree with Hugo that it would be useful if we could find a way to
help out automated dependency checkers.

-- Johan

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