Re: equality as a variable

A. Sinan Unur <1usa@xxxxxxxxxxxxxxxxxxx> wrote in comp.lang.perl.misc:
> Brian Wakem <no@xxxxxxxxx> wrote in news:3q58ibFd6ikpU1@xxxxxxxxxxxxxx:
>
> > Shiraz wrote:
> >
> >> i need to put the equality in an if statement as a variable
> >>
> >> ($val1, $val2, $comp) = (1,2,"gt");
> >> if ($val1 $comp $val2)
> >> { print $val1; }
> >> i couldnt find anything in the achives.... if some knows it, please
> >> let me know.. or point me in a direction i can research the method.
> >> thanks
> >
> >
> > if (eval("$val1 $comp $val2")) {
> > ...
> > }
> >
>
> Hmmm ... Sorry, I am going to go with hash based solution:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> use Carp;
>
> my %handlers = (
> '>' => sub { $_[0] > $_[1] },
> '<' => sub { $_[0] < $_[1] },
> '>=' => sub { $_[0] >= $_[1] },
> '<=' => sub { $_[0] <= $_[1] },
> '==' => sub { $_[0] == $_[1] },
> '!=' => sub { $_[0] != $_[1] },
> '<=>' => sub { $_[0] <=> $_[1] },
> );

I'd use the hash *and* eval:

my %handlers = map { $_ => eval "sub { \$_[0] $_ \$_[ 1] }" }
qw( > < >= <= == != <=>),
# qw( gt lt ge le eq ne cmp),
;

That string-eval is perfectly safe, everything comes from inside the source.

Anno
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