On Jun 17, 2014, at 1:02 PM, SSC_perl wrote:
> What's the best way to stop undefined warnings for code like this:
>
> $data->{'image'} = CopyTempFile('image') if ($main::global->{'admin'} &&
> $main::global->{'form'}->{'image_upload'} ne '');
>
> CGI::Carp gives the following:
>
> [Tue Jun 17 14:54:36 2014] admin.cgi: Use of uninitialized value in string ne
> at admin.cgi line 219.
>
> I know that I can surround the section with
> {
> no warnings 'uninitialized';
> ...
> }
>
> or I could add a check for defined-ness as follows:
>
> $data->{'image'} = CopyTempFile('image') if ($main::global->{'admin'} &&
> defined $main::global->{'form'}->{'image_upload'} &&
> $main::global->{'form'}->{'image_upload'} ne '');
>
> Is there a better way to stop this warning in situations like this?
> I'd like to keep these warnings from filling up the log.
"Best" and "better" are subjective terms about which people will argue.
Me, I would split your one, long line into several lines and use a temporary
variable to hold the possibly undefined value and assigning '' to it if it is
undefined:
my $upload = $main::global->{'form'}->{'image_upload'} || '';
if ($main::global->{'admin'} && $upload ne '' ) {
$data->{'image'} = CopyTempFile('image');
}
I find that much more readable and will not generate any undefined warnings.
Note that later Perls can use the // operator in the first line to test the
"definedness" of the hash value:
my $upload = $main::global->{'form'}->{'image_upload'} // '';
but there is no practical instance in this case. There would be if you needed
to distinguish zero or '' from undef.
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