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Re: bug report

From: Paul D. Smith
Subject: Re: bug report
Date: Mon, 5 Jan 2004 10:58:41 -0500

%% "Sandeep Nema" <address@hidden> writes:

  sn> has been set in any way, including to the empty value


  sn> You mentione in your previous answer that "?:" is not supported
  sn> syntax, shouldn't it give any kind of  error if its used in the
  sn> makefile.

Just because the syntax doesn't do the same thing it does in other
makes, doesn't mean that it's not legal syntax in GNU make.

  ps> Since you didn't specify exactly what behavior "?:" provides I
  ps> can't say for sure, but look up the ?= assignment operator in the
  ps> GNU make manual.

  sn> X = $(EX_X?:ADD_X))

  sn> if EX_X is NOT defined, X = ADD_X
  sn> else X contains an empty value.

Yes, but as I mentioned you didn't specify what "defined" means (your
reply above makes it clear now).

The only way to do exactly the above is using if statements.  You can
combine them with call, eval, etc. to define your own macro to make it
slightly easier for the user, if you use this syntax a lot.

The ?= operator will do what you want if you're trying to define a
variable to a value if it itself doesn't have one, but it won't help if
you're trying to define a variable to a value if some other variable
doesn't have one.

 Paul D. Smith <address@hidden>          Find some GNU make tips at:
 http://www.gnu.org                      http://make.paulandlesley.org
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist

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