Re: Deferred->immediate variable reassignment trick.

[Kaz Kylheku]

On 2023-06-20 12:55, Paul Smith wrote:
> I don't understand how this is different than just:
> 
>     IMPORTANT_VAR := $(IMPORTANT_VAR)
> 
> If the user specifies an override of the variable on the command line
> then the value in the makefile will never be used, so the shell command
> will never be invoked.

If I just have this:

  IMPORTANT_VAR := $(shell sh -c "echo calculate; echo executed 1>&2")

and do "make IMPORTANT_VAR=alternative", I still see "executed"
on standard output. (In an installation with Make 4.1.)

If I just have this:

  IMPORTANT_VAR = $(shell sh -c "echo calculate; echo executed 1>&2")

and use $(IMPORTANT_VAR) in multiple places, I see multiple "executed",
of course.