Re: Question about use of $(wildcard) and $(foreach)

[Mike Shal]

On 4/16/07, Rick Flower <address@hidden> wrote:
> I took a different approach and listed all of the possible paths in a
> variable called "OBJDIRS" and wanted to write some makefile 'code' that
> could pick out the only one that exists for the directory tree where
> Make was invoked from.. Below is what I was trying but found that it
> would only return a valid OBJDIR when the valid directory was at the end
> of the list (IIRC) or other odd conditions:
>
> OBJDIR =
> OBJDIRS := \
>            ../../${proc}/obj/${target) \
>            ../../${target}/obj \
>            ../../obj/${target}

First: note that you have "${target)" - you should probably use either
"${target}" or "$(target)", rather than mix and match your parens :).

> find_files  = $(if $(wildcard $(dir)),OBJDIR=${dir})
> OBJDIR := $(foreach dir,$(OBJDIRS),$(find_files))

$(wildcard) already operates separately on each element in the list,
so you don't need to wrap it with a $(foreach) in this case. Also, you
wouldn't want OBJDIR= in the $(if) statement, since you aren't
actually executing statements there.

Anyway, this could probably be much simplified by just doing:

OBJDIR := $(firstword $(wildcard $(OBJDIRS)))

The $(firstword) is used in case more than one directory exists - this
would just pick the first one. You probably also want to check if no
match was found and print an error, like:

ifeq (,$(OBJDIR))
 $(error No directory found)
endif

Hope this helps,

-Mike