Re: Sorting result of function call

[sgt]

I can confirm the same result on cygwin with 5.8.7:

 
% stephan@armen (/home/stephan) %
% perl -w sort_context.px
get_keys

called:array:13
called:array:13
called:array:13
called:array:13

deparse tells us:

% stephan@armen (/home/stephan) %
% perl -MO=Deparse sort_context.px
use warnings;
use strict 'refs';
my(%h) = (1, 2, 3, 4);
sub say {
    print @_, $/;
}
sub get_keys {
    print 'called:';
    if (wantarray) {
        print 'array:';
    }
    else {
        print defined wantarray ? 'scalar' : 'void';
    }
    return keys %h;
}
say sort('get_keys');
say((sort get_keys ()));
say sort(&get_keys);
say sort(&get_keys());
say sort(@{[get_keys()];});
say sort(@{[get_keys()];});
sort_context.px syntax OK

so in the first case get_keys gets interpreted as a string. seems like a bug (an old one...) with use strict; (especially if one follows the principle of least surprise) still it's true that it is quite ambiguous... hth --stephan

[Hofmator]

Thanks for trying that out. Deparse is a good idea, I get the same results as you except for case two, where my Deparse says

say sort('get_keys' ());

vs your

say((sort get_keys ()));

Interestingly, feeding my Deparse output back to perl leads to a syntax error. Your version seems to indicate what perl is doing here. Trying to sort the empty list () with the compare-function get_keys, hence the empty return.