Re: HELP! $(wildcard ) function failed very strangely

[Kristof Provost]

On 2007-09-30 13:39:47 (+0000), Chen??????Jun?????? <address@hidden> wrote:
> Thanks Kristof, and I tried your suggestion(introducing the MATCH variable) 
> but
> it behaves the same as my original makefile.
> 
> 
> The makefile(t.mk) according to your suggestion is in the mail attachment.
>  
> Further more, you said "The $(wildcard ) is evaluated when the rule is
> parsed", while I find the gnu official manual does not say that. According
> to "3.9 How make Reads a Makefile", expansion of the $(wildcard ) function,
> like other functions, is deferred when the commands for the rule(prj_count) 
> are
> to be executed. 
The commands are deferred, but the expansion of the variables is not.

Try the following test case:

testrule:
    touch test
    echo $(wildcard test)

The echo command will not output anything (at least, if 'test' didn't
exist when make started. 

> Can you or someone give further explain?
It looks like I wasn't quite right though. My proposal still doesn't
work, as the $(match) variable is expanded when the rule is parsed, not
when it's executed. SECONDEXPANSION could help, but that only works for
prerequisites.

The only solution I see is to use shell tests:

testrule:
    touch test
    if [ -f test ] ;\
    then \
        echo "test exists" ;\
    fi

Does anyone else know a better way of handling this?

Regards,
Kristof

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