From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] p9p mk issue 
From: "Russ Cox" <rsc@swtch.com>
Date: Thu, 22 Nov 2007 14:48:43 -0500
In-Reply-To: <20071122174322.E07B55B3E@mail.bitblocks.com>
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> That was the first thing I tried -- didn't I mention that in
> my original email on this?  But setting MKSHELL in an
> included file works for only that file and then we are back
> to sh.
> 
> Try this and watch it fail:
> 
> echo MKSHELL=rc > mkshell
> echo '
> <mkshell
> all:
> 	for (i in a b)
> 		echo $i
> ' > mkfile
> mk

That's not what I meant.  I meant that if you have
complicated things like loops then you can put those
recipes all in one file (that also contains MKSHELL=rc)
and just include it.  Essentially all the Plan 9 mkfiles
set HFILES, OFILES, TARG, and then include mkone,
mkmany, and mksyslib.  Only those would possibly
need to declare a MKSHELL.

As another example, p9p goes farther than Plan 9 in this
respect and has a $PLAN9/src/mkdirs that contains
the typical loop over directories and defines not just
"all" but "clean" and "nuke" and the rest.  Clients just
define a variable and then include mkdirs:

	<$PLAN9/src/mkhdr

	LIBS=common
	PROGS=smtp alias fs ned q send marshal vf 

	# libs must be made first
	DIRS=$LIBS $PROGS

	<$PLAN9/src/mkdirs

If you were going to use rc syntax in mkdirs, then it would
be the only file that needs to say MKSHELL=rc.

Russ


P. S.  I realize it's suboptimal to have to set MKSHELL in each mkfile
that uses rc-specific features, but it's the only way that scales.