On Wednesday 20 March 2002 20:48 pm, Diane Holt wrote:
> --- stephan beal <[EMAIL PROTECTED]> wrote:
> > i have a suggestion for the if/unless clauses:
> >
> > Rename them to ifset and unlessset. The reason for this is that they
> > have behaviour which is counter-intuitive for most programmers
> > in that they work if the var is set to *any* value, regardless of
> > the true/false interpretation of the var.
>
> I don't find it counter-intuitive. The if/unless attributes take the name
> of a property, not a reference to its value (ie., "foo", not "${foo}") --
> nor does setting a property to "true" or "false" mean anything special,
> generally, since they're just the strings t-r-u-e and f-a-l-s-e.
It's counter-intuitive when compared to the 'if' feature every programming
language in the world. The strings true/false/yes/no DO have special meanings
in ant - they are converted to the boolean values 'true' in many contexts.
The fact that they aren't treated that way in some contexts (if/unless) is
confusing - it's inconsistent not only with other languages, but also with
ant's own normal handling of true/false/yes/no.
In a "normal" scripting language you could do this:
$foo = false;
if( $foo ) {
print "blah";
} # this'll never run
in ant, however, it would run.
Actually, in Perl it would evaluate to true if $foo was the string "blah",
and in that sense it behaves like ant's 'if'. However, if $foo is set to "0",
then it would evaluate to false in Perl, but true in ant (in the 'if'
context, at least). i see your point, but i am still befuddled by the
inconsistency. i'm used to it now, so i understand how to use it, but i shake
my head every time i do ;).
A different, backwards-compatible feature which might make the use of 'if'
more useful is adding an 'unset' attribute to <property>:
<property name='foo' unset/>
Then we can be sure that ${foo} is not set, in the case that we want to unset
it for some tests, for example.
----- stephan
Generic Universal Computer Guy
[EMAIL PROTECTED] - http://www.einsurance.de
Office: +49 (89) �552 92 862 Handy: �+49 (179) 211 97 67
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