On Wed, 20 Sep 2000, Robert Hegemann wrote:
> Takehiro Tominaga schrieb am Mit, 20 Sep 2000:
> > >>>>> "R" == Robert Hegemann <[EMAIL PROTECTED]> writes:
> >
> > R> I'm using GNU Make version 3.77, does above work for other Make
> > R> versions?
> >
> > Yes, it does not work on 3.77. so I upgraded it 3.78.1 and it works fine.
> > ---
> > [EMAIL PROTECTED] // may the source be with you!
>
> What is the benefit of ?= instead of =
-----
There is another assignment operator for variables, `?='. This is
called a conditional variable assignment operator, because it only has
an effect if the variable is not yet defined. This statement:
FOO ?= bar
is exactly equivalent to this (*note The `origin' Function: Origin
Function.):
ifeq ($(origin FOO), undefined)
FOO = bar
endif
Note that a variable set to an empty value is still defined, so `?='
will not set that variable.
-----
> so that I should
> upgrade from 3.77 to 3.78.1 ???
Try FreeBSD. A simple:
$ cd /usr/ports/devel/gmake
$ make all install
Will do everything for you :)
BTW 3.79.1 is the latest version of GNU make.
Mark Powell - UNIX System Administrator - The University of Salford
Academic Information Services, Clifford Whitworth Building,
Salford University, Manchester, M5 4WT, UK.
Tel: +44 161 295 5936 Fax: +44 161 295 5888 www.pgp.com for PGP key
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