Subject: Re: make(1) question; purpose of ${ :? : }
To: Luke Mewburn <>
From: Simon J. Gerraty <>
List: tech-toolchain
Date: 01/09/2004 00:27:17
>On Fri, 9 Jan 2004 11:23:23 +1100, Luke Mewburn writes:
>>what limitations are there on the expression before the ':?'  ?
>>can we do stuff like
>>	${defined(FOO)||${BAR}!=3D"" :?true:false}

Actually you can - sort of.
Problem is you have to prevent ${BAR} being expanded
until it is passed to Cond_EvalExpression().

So the following:

A?=$${USER} == "$B"

	@echo "The answer for '$A' is ${$A:?yes:no}"


$ make -f /homes/sjg/make-tests/ternary x  
The answer for 'sjg == x' is no
$ make -f /homes/sjg/make-tests/ternary x B=sjg
The answer for 'sjg == sjg' is yes

But you can't put the expression directly into the ${:?yes:no} bit.