Re: "no rule to make target" when target is a variable

[Brendan Bridgford]

Thanks Paul. 

I understand now why this doesn't work but I may have mislead you on my end goal.  Is there a way to set a global variable from the context of a target?

Here's a fuller picture of what I'm trying to do (pretend for a moment that my syntax works):

.PHONY = foobar
foobar : a = foo
foobar : b = bar

.PHONY = poobar
poobar : a = poo
poobar : b = bar

c=$(a)$(b)

$(c) : 
  echo $(a)rules

I want to apply essentially the same rules to multiple targets without explicitly listing each target (i.e. a variable target name), while retaining control over what gets made (i.e
. I don't want "c = foobar poobar").  Is there a better way of going about this?

Thx,
--Brendan

On 12/5/06, Paul Smith < address@hidden> wrote:

On Tue, 2006-12-05 at 20:19 -0500, Brendan Bridgford wrote:
> I'm trying to use a variable as a target without much luck.

> .PHONY = foobar
> foobar : a = foo
> foobar : b = bar
> c=$(a)$(b)

>
> When I invoke
> >make foobar
>
> ... it returns:
> make: *** No rule to make target `foobar'.  Stop.

Indeed.

> Why isn't it working when I use the variable $(c) as a target?  I'm
> using GNU Make 3.80 for i686-pc-cygwin.

The synaxt "target : variable = value" defines a target-specific
variable.  That means that the variable only has this value in the
context of that target: for example inside the command scripts for that
target.

You are trying to set a and b as variables in the context of the foobar
target, but then use them (in c) in the global scope, outside of the
scope of the target foobar.  That can't work.

If you do this:

  a = foo
  b = bar

  c = $(a)$(b)

  $(c): ; @echo $@

it will work as you expect.

--
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Paul D. Smith < address@hidden>          Find some GNU make tips at:
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