On Fri, 2005-01-28 at 08:21, Robert P. J. Day wrote:
> ${SUBDIRS}:
> @echo "My target is [EMAIL PROTECTED]"
> @echo "My makefile variable contains [EMAIL PROTECTED]"
> ifneq "[EMAIL PROTECTED]" ""
> @echo "Yup, that variable is set."
> endif
>
> i want to call this with something like:
>
> $ make d2_MAKEFILE=d2make d2
>
> and be able to test whether the corresponding variable is set within
> the rule.
That doesn't work because the ifneq is handled at Makefile parse time
and hence $@ is unset and if ends up doing
ifneq "${_MAKEFILE}" ""
which assuming you haven't set _MAKEFILE somewhere is going to fail.
Since $@ is only known at rule run time and preprocessor stuff like
ifneq is done at parse time there's no way to mix the two.
You could use a $(if) instead like this:
${SUBDIRS}:
@echo "My target is [EMAIL PROTECTED]"
@echo "My makefile variable contains [EMAIL PROTECTED]"
@$(if [EMAIL PROTECTED],echo "Yup that variable is set.")
Note that I took the comma out of the "Yup..." otherwise the $(if)
interprets that , as a parameter separator.
John.
--
John Graham-Cumming
Home: http://www.jgc.org/
Work: http://www.electric-cloud.com/
POPFile: http://getpopfile.org/
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