Re: Undef and Unitialized Issue

In more general terms, I typically use something like this to silence those warnings (assuming a value of undef is not an error):

my $string_var = defined( $input_field ) || '';

# or

if ( ($string_var || '') !~ /some_pattern/ ) {
    ...
}
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If in fact undef is an error I would generally use something along this line:

croak "HEY! Why am I not defined?" if !defined( $input_field );
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You must always remember that the primary goal is to drain the swamp even when you are hip-deep in alligators.

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Re^2: Undef and Unitialized Issue by afoken (Chancellor) on Apr 04, 2015 at 09:11 UTC
`my $string_var = defined( $input_field ) \|\| '';` This will set `$string_var` either to `1` or to `""`, no matter what `$input_field` was set to. Looking at the variable names, this is hardly what you want. `($string_var \|\| '')` This evaluates to `""` if `$string_var` is `undef`, `0`, or `"0"`. You don't want to change "0" or 0 to the empty string, do you? Why don't you use the defined-or operator `//`? `$string_var//''` evaluates to `""` only if `$string_var` is `""` or `undef`. `0` and `"0"` are not changed. Ancient perl versions have no defined-or-operator, so you have to resort to something like `$never_undef=defined($perhaps_undef) ? $perhaps_undef : '';` for code that is expected to work with ancient perl verisons. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re^3: Undef and Unitialized Issue by boftx (Deacon) on Apr 06, 2015 at 15:18 UTC
You are correct, I was thinking of where I use `delete($input) \|\| ''` to ensure a defined value and "0" is not a concern. The second form you present (using `?:`) is more correct in the general case. As for using an "ancient version of Perl" I don't have a choice at $work, we are stuck on 5.8.9 for at least a few more months. You must always remember that the primary goal is to *drain the swamp* even when you are hip-deep in alligators.	[reply] [d/l] [select]