You may be able to exploit the ~ operator, it has deep
knowledge of Perl's internals. For example:
$string = "1";
$integer = 1;
print ~$string; # Prints an extended character
print ~$integer; # Prints 4294967294
Much easier than messing with perlguts. But there's
one caveat: using ~ on a string with extended characters
results in ASCII characters; that is
~chr(205)
is "2". Assuming your definition of "string" does not
include extended characters (only ASCII), you should be
able to get away with a function like this:
sub is_integer
{
return (~$_[0] =~ m/^[0-9]+$/) ? 1 : 0;
}
print "1 ", is_integer(1), "\n"; # 1 ok
print "'1' ", is_integer('1'), "\n"; # 0 ok
print "chr(205) ", is_integer(chr(205)),"\n"; # 1 not ok
That said, be careful with this power. You don't want
to confuse your users. Problems occur when reading data
from files or console, as everything read is a string unless
explically changed via +0. This also doesn't work for
floating point. But sometimes it may have useful uses.
Hope this helps,
Jeff Connelly