Re: automake/44: conditional redefinitions (Was: Re: Automake 1.6.3 issue)

[Alexandre Duret-Lutz]

>>> "Akim" == Akim Demaille <address@hidden> writes:

[...]

 Akim> Nevertheless, I agree a means to install defaults would
 Akim> be most welcome.

 Akim> I suggest introducing

 Akim> foo ?= bar

 Akim> Which is always valid, but with a clear semantics.

Assuming your semantic is that of BSD make: "assign unless set" [*],
I can see how this help in

  if COND1
    foo = mumble
  endif
  if COND2
    foo = blurgle
  endif
  foo ?= else

But I fail to see how you'd use this to override a default
value whose definition has been included from elsewhere.

(Unless inclusions of fragments defining default variables are
done at the end of Makefile.am -- but this raises a few other
issues.)

[...]

[*] IIRC someone once sent a patch against Automake to introduce
`?=' as "assign and allow future redefinitions".
-- 
Alexandre Duret-Lutz