[tpm] dereferencing anonymous hashes

[Liam R E Quin]

On Thu, 2007-04-12 at 11:21 -0400, Uri Guttman wrote:

> useful? that is what it is designed for. it was taken from c which has
> the same operator but no list context to confuse things.

The , in C that's used in parameter lists (for example), as in
    int m = max(3, 12, 9, 76);
is like the comma in a Perl list,
    my $m = max(3, 12, 9, 76);
which is not at all like
    my @mm = max(3, 12, 9, 76);
:-)

Similarly, the C comma operator, really only used in a few
places these days because it's dangerous otherwise, is the same
as semicolon except that it doesn't terminate the statement, so

    if (e) a = 3,
    b = 6,
    c = 12;

is the same as

    if (e) {
        a = 3;
        b = 6;
        c = 12;
    }

except harder to follow.  In Perl, you have to use the braces, so the
second form is enforced, but you can still do things like

for ($i = 1, $j = 6; $i < 10; $i++, $j++) {
    stuff
}

and that's also the main place the comma operator is used in C.

I'd prefer in most cases
for (my $i = 1; $i < 10; $i++) {
    my $j = $i + 5;
    stuff;
}

because the relationship between in and j is now made explicit.

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org www.advogato.org