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Re: Immediate and deferred expansion documentation rewording


From: Maris Razvan
Subject: Re: Immediate and deferred expansion documentation rewording
Date: Wed, 2 Oct 2019 00:42:21 +0300

>
> > the value in the definition of a recursively
> > expanded variable is considered to be a "construct", therefore it can
> > also be regarded as a "deferred construct"?
>
> Yes.  I think it's useful to consider:
>
> nam = exp
>
> ... as a construct of at least two sections, because nam is immediately 
> evaluated, while the evaluation of exp is deferred.

As in my original question, I agree that the documentation implies
that constructs contain sections, some of which are immediately
expanded, while others have a deferred expansion. However I do not
think the documentation intends for these sections to be also regarded
as "constructs" (I believe the term "constructs" refers only to the
top-level components of a makefile: rules, variable definitions,
directives and comments).

> > how can that value "appear in an immediate context"?
>
> It can't: that was my point in the last sentence of my previous post.  Given:
>
> nam = exp
>
> It's when $(nam) appears in an immediate context that exp gets evaluated.  
> exp needn't itself appear again.

But if one considers the value in a recursively expanded variable to
be a "deferred construct", this type of "deferred construct" cannot
"appear in an immediate context", as you said, therefore the wording
from the manual: "Expansion of a deferred construct is not performed
until either the construct appears later in an immediate context" is
wrong, as there are no "deferred constructs" that can appear in an
immediate context.

However, if the documentation intended for a recursively expanded
variable (the variable as an entity, not some part of the parse tree)
to be considered a "deferred construct", then this "deferred
construct" can appear in an immediate context (it can be referenced,
and its expansion would mean the expansion of the value specified in
its definition). However, this meaning of "construct" does not match
the meaning of "construct" used in the previous sentences.

Either way the term "deferred construct" is interpreted, I still
believe that this paragraph is not clear or consistent with regards to
terminology.



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