EXPLICIT_PACKAGE_DEPENDS=true

[Alexander Leidinger]

On Sat, 2 Jun 2012 06:18:24 -0400 Carmel <carmel_ny at hotmail.com> wrote:

> I have seen the "EXPLICIT_PACKAGE_DEPENDS=true" knob mentioned in
> several posts. I have three questions in its regards.
> 
> 1) Exactly what does it do? I cannot seem to locate a definitive
> answer.

Currently if port A depends upon B and B upon C you will get a
dependency recorded in A upon C. If you activate this know you will not
get the A->C dependency, only the A->B and B->C ones.

> 2) If this is a "good thing" then why is it not a default setting?

If port B and C is a lib, and A is linked to B, A also contains a
reference to C, even if A only references functions from B. For libs
which are build with libtoo, this can be changes with a patch to
libtool (my experience with this is based upon an investigation
several years ago, I don't know if this changed, but I assume it
hasn't). There where some good reasons to not activate this
functionality in libtool back when I had a look at it, I don't know if
those reasons still apply.

> 3) What benefits could I expect to see from using this setting?

Less ports to recompile when a library changed in a way which requires
a rebuild of all programs which depend upon it.

Bye,
Alexander.

-- 
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