Re: most appropriate return data type

Which is it, an array or a list?

use warnings;
use strict;

sub mysub1 {
    my @fred = qw(The quick brown fox);
    
    return @fred;

}

sub mysub2 {
    return qw(The quick brown fox);

}

my $x = mysub1();
print "x: $x\n";

my $y = mysub2();
print "y: $y\n";
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Gives:

x: 4
y: fox
[download]

You could always use wantarray to return a list or a scalar, depending on the context.

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Re^2: most appropriate return data type by Anonymous Monk on Feb 19, 2010 at 15:52 UTC
Why does $y hold 'fox'? I know that mysub2() returns a list, but I don't know why $y gets assigned to 'fox'.	[reply]
Re^3: most appropriate return data type by shmem (Chancellor) on Feb 19, 2010 at 16:09 UTC
The caller forces context on the return. The return value is the result of the evaluation (in the context of the caller) of the last expression in a subroutine (or the expression given to `return`). So.. an array in scalar context is the number of items in it. in scalar context the expression `('a','b','c')` isn't a list, it's a chain of comma operations: In scalar context, the comma operator throws away it's left operand and evaluates the right operand. So the result is `c` the `qw//` operator is the comma operator in disguise See perlop. Ah, and 'fox' gets assigned to '$y' </nitpick> ;-)	[reply] [d/l] [select]
Re^4: most appropriate return data type by merlyn (Sage) on Feb 19, 2010 at 16:43 UTC
the qw// operator is the comma operator in disguise It is now. It used to be the `split` function, in which case, you'd get a split-in-a-scalar-context which would clobber `@_` and trigger a warning and return 4. :) -- Randal L. Schwartz, Perl hacker The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.	[reply] [d/l] [select]
Re^5: most appropriate return data type by TGI (Parson) on Feb 24, 2010 at 20:38 UTC
Re^3: most appropriate return data type by cdarke (Prior) on Feb 19, 2010 at 16:44 UTC
I can't improve on shmem's reply, but that is exactly the reason why you should be clear as to which type you intend to return - and also why you might wish to use wantarray to check for scalar context.	[reply]