Re: Named parameters in make?

[John Dill]

Date: Sat, 11 Jun 2011 01:33:42 +0200
From: grischka <address@hidden>
Subject: Re: Named parameters in make?
Message-ID: <address@hidden>
Content-Type: text/plain; charset=UTF-8; format=flowed

>> Over my time using make I know I've read section 8.8 "The eval Function" a
>> number of times. But the implication of this sentence didn't hit me until I
>> saw your example:
>> 
>> "The argument to the eval function is expanded, then the results of that
>> expansion are parsed as makefile syntax."
>
>Reason why eval is difficult to understand is that there is no good
>reason to have it, in the first place.
>
>For example one can write:
>
>    all_rule = all : ; echo $$@
>    $(all_rule)
>
>which expands the macro $(all_rule) and does parse the result as
>makefile syntax.  That is everything said in the above statement,
>just without 'eval'.

The only use I have for using $(eval) directly is setting a variable within a 
user-defined function, which is quite useful in some contexts.

set=$(eval $1:=$2)

I use this behavior of $(eval) quite frequently.

Best regards,
John D.

<<winmail.dat>>