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=head1 TITLE
Implicit counter in for statements, possibly $#.
=head1 VERSION
Maintainer: John McNamara <[EMAIL PROTECTED]>
Date: 16 Aug 2000
Last-Modified: 16 Aug 2000
Version: 2
Mailing List: [EMAIL PROTECTED]
Number: 120
=head1 ABSTRACT
The syntax of Perl style C<for> statements could be simplified by the
introduction of an implicit counter variable. The deprecated variable
C<$#> could be used for this purpose due to its mnemonic association
with C<$#array>.
=head1 DESCRIPTION
The following discussion makes no distinction between the C<for> and
C<foreach> statements.
The use of the C<foreach> statement or the C<for> statement in
conjunction with the range operator, C<..>, are generally seen as good
idiomatic Perl:
@array = qw(sun moon stars rain);
foreach $item (@array) {
print $item, "\n";
}
as opposed to the "endearing attachment to C" style:
for ($i = 0; $i <= $#array; $i++) {
print $array[$i], "\n";
}
However, the latter format is often more convenient if you need to
keep track of the array index as well as iterating over the array:
for ($i = 0; $i <= $#array; $i++) {
print $array[$i], " is at index ", $i, "\n";
}
is more succinct than:
$i = 0;
foreach $item (@array) {
print $item, " is at index ", $i, "\n";
$i++;
}
The addition of an implicit counter variable in C<for> statements
would lead to a more elegant syntax. It is proposed that the
deprecated variable C<$#> should be used for this purpose due to its
mnemonic association with C<$#array>. For example:
foreach $item (@array) {
print $item, " is at index ", $#, "\n";
}
The variable C<$#> currently holds the output format for printed
numbers.
=head1 IMPLEMENTATION
Not sure. However, consideration would have to be given to nested
C<for> statements and how the variable would be affected by C<local>.
=head1 REFERENCES
perlvar
Alex Rhomberg proposed an implicit counter variable on clpm:
http://x53.deja.com/getdoc.xp?AN=557218804&fmt=text and
http://x52.deja.com/threadmsg_ct.xp?AN=580369190.1&fmt=text
Craig Berry suggested C<$#>:
http://x52.deja.com/threadmsg_ct.xp?AN=580403316.1&fmt=text
