•Re: Checking for the existence of a passed parameter.

use CGI qw(param);
...
my $verify = param("verify");
if (defined $verify) { # was passed...
  if ($verify eq "yes") { # was yes...
  } else { # not yes...
  }
} else { # not passed...
}
[download]

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Comment on •Re: Checking for the existence of a passed parameter. Download Code

Replies are listed 'Best First'.
Re^2: Checking for the existence of a passed parameter. by Aristotle (Chancellor) on Nov 11, 2003 at 20:02 UTC
That's somewhat hard to read IMO. It hides the fact that this really is a tristate switch. I'd probably check for not-definedness separately. `my $verify = param("verify"); if (not defined $verify) { # wasn't even there # ... # return, exit, last, or whatever here } if($verify eq 'yes') { # ... } else { # ... }` [download] This is Perl, let's not be writing Pascal code. g Makeshifts last the longest.	[reply] [d/l]
•Re: Re^2: Checking for the existence of a passed parameter. by merlyn (Sage) on Nov 11, 2003 at 20:21 UTC
But your code generates warnings when comparing $verify to 'yes' if it's also undef, unless you're absolutely sure that your code doesn't fall out the bottom. I'd write that like this, if you wanna flatten the nesting: `if (not defined $foo) { ... undef ... } elsif ($foo eq 'yes') { ... yes ... } else { ... everything else ... }` [download] -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply] [d/l]
Re^4: Checking for the existence of a passed parameter. by Aristotle (Chancellor) on Nov 11, 2003 at 20:34 UTC
That's why I commented that there should be a "return, exit, last, or whatever" at the end of the first block. Your version is what I should have arrived at, though. (I was actually going for a single-if-series solution, but don't know why it didn't occur to me to check the definedness up front. I was irked by having to `defined $foo and ...` in all conditions before the else-block. Heh. I'm embarrassingly slow lately.) Makeshifts last the longest.	[reply]