Re: is this a feature or a bug?

[Sam Ravnborg]

On Tue, Nov 23, 2010 at 11:40:14AM -0800, James Sarrett wrote:
> Hi all,
>
> I was trying to write a very simple Makefile this morning, and was  
> stymied!  What I thought I meant was this:
>
> xrcs := *.xrc
> py_xrcs := $(xrcs:.xrc=_xrc.py)
>
> %_xrc.py: %.xrc
>     pywxrc -pv $<
>
> all: $(py_xrcs)
>
> I have 2 .xrc files which need to be turned into _xrc.py files via  
> pywxrc.  I'm using GNU make 3.81 on Ubuntu 10.10 (maverick meerkat).   
> What appears to actually happen is that the variable py_xrcs ends up  
> with only the first filename returned by *.xrc translated to  
> file1_xrc.py.  I have found the workaround to be defining xrcs like this:
>
> xrcs := $(wildcard *.xrc)
>
> This seems like it should not be required.  Is this a bug in patsubst?

>From the manual:
   Wildcard expansion is performed by `make' automatically in targets
   and in prerequisites.  In commands the shell is responsible for
   wildcard expansion.  In other contexts, wildcard expansion happens only
   if you request it explicitly with the `wildcard' function.

So the wildcard is needed because you want the expansion to happen
outside the prerequisites/targets.

        Sam