IO::Prompt warning

DanieleFerone has asked for the wisdom of the Perl Monks concerning the following question:

Why this code:

#! /usr/bin/perl -w

use strict;
use IO::Prompt;

while (my $x = prompt "x: ", -while => '') {}
[download]

give me this warning?

Use of uninitialized value in pattern match (m//) at /usr/local/share/
+perl/5.8.8/IO/Prompt.pm line 91.
[download]

Thanks.

Comment on IO::Prompt warning Select or Download Code

Replies are listed 'Best First'.
Re: IO::Prompt warning by kyle (Abbot) on Jul 11, 2008 at 16:56 UTC
I notice that the warning goes away if you use warnings instead of using the `-w` flag.	[reply] [d/l]
Re: IO::Prompt warning by pc88mxer (Vicar) on Jul 11, 2008 at 16:47 UTC
It's a bug. You get the same result if you run the `while_until.pl` example in the `IO::Prompt` distribution with `use strict`. The problem is that a `next unless defined` has to be added in the `_get_prompt` routine at this point (line 91): `for (my $i = 0 ; $i < @data ; $i++) { local *_ = \($data[$i]); + next unless defined; if (ref eq 'HASH') { splice @data, $i + 1, 0, %$_; }` [download] The `for` loop removes arguments supplied to `prompt` by `undef`-ing them in the array `@data`, but the index `$i` still only advances by one. When an option with an argument is encountered, both the option switch and the argument are `undef`-ed, but the loop will still inspect the position occupied by the option's argument.	[reply] [d/l] [select]
Re: IO::Prompt warning by psini (Deacon) on Jul 11, 2008 at 16:41 UTC
Maybe IO::Prompt doesn't like an empty pattern in -while argument. Anyway I think it is useless to specify it. Rule One: "Do not act incautiously when confronting a little bald wrinkly smiling man."	[reply]