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Re: Clarification on Scoped variables

From: Paul Smith
Subject: Re: Clarification on Scoped variables
Date: Fri, 02 Dec 2011 15:24:45 -0500

On Fri, 2011-12-02 at 14:42 -0500, AB wrote:
> Hi:
> I wanted to clarify if the following behavior of scoped variables
> (target specific varibles) is by design. Consider the code below,
> where use of the target "" is for collecting meta data about,
> "a" without building "a"
> .PHONY : test
> a : var_def := 1
> a :
>       @touch $@
> # Make var_def visible to
> a :
> :
>       @echo VAR_INH: $(var_def)
> # This does not emit the value of var_def as 1
> test :
> As I understand that when Make looks at building a target, it only
> looks at dependencies that effect the target directly or indirectly.
> But this eliminates any scope for looking into any inherited
> variables. Is this by design?

Yes, it's working as expected.  The variable inheritance is computed
dynamically as make builds the targets, so it's not sufficient to
declare a prerequisite relationship, you also have to be building the
target as the result of that prerequisite in order to see its variables.

 Paul D. Smith <address@hidden>          Find some GNU make tips at:            
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist

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