Re: how to create a single rule to build a directory as necessary

[Sam Steingold]

Paul Smith wrote:
> On Tue, 2009-09-22 at 11:11 -0700, Philip Guenther wrote:
> > > > which by the way, is not well-formed; it should be:
> > > >
> > > >        mkdir -p $@ && cd $@ && $(MAKE)
> > > I am afraid I cannot use the "gnuisms" (as they were called by a
> > NetBSD user
> > > who was bitten by these variables when I used them)
> > Whoever told you that is sadly mistaken.  The '@' and 'MAKE' variables
> > are both specified by the POSIX/SUS standard for make and were present
> > in 4.2 BSD!  It's handy to keep around a link to the standards
> > specification for quoting at people that are, uh, confused about
> > history and requirements.  Here's the link for 'make' from the Single
> > UNIX Standard, Issue 6.
> >
> > http://www.opengroup.org/onlinepubs/009695399/utilities/make.html
>
> The NetBSD user is definitely incorrect in calling these "GNUisms"; they
> are part of the POSIX spec as you point out.
>
> However, it is true that using $@ in they way I suggested is not 100%
> portable.
>
> In one of those bizarre brain-lapses that make you go "huh?", original
> versions of make only defined automatic variables like $@ for implicit
> (suffix) rules.  They were not defined for explicit rules.  Some
> instances of make still do not support them in explicit rules, so
> maximally portable makefiles can only use $@ in suffix rules.

this is precisely what the NetBSD user said.
sorry about the confusion.

actually, POSIX requires that $@ is defined for _all_ rules.
however, "The meaning of the $< macro shall be otherwise unspecified" - for 
non-inference rules, that is...