Is there a canonical practice for assigning value to an argument which, if "empty", is assigned a "default_value"? Here, "empty" is defined as an argument value which is either undef or the null string ('').

Notably, 0 (or perl false) is a valid, non-"empty" value, which rules out the construction $arg = (shift ||= 'default_value').

This is my current construction (note the use of the v5.10+ logical-or operator, //): 

use 5.010;
use strict;
use warnings;

sub f { # ( [$:arg] )
    my $arg = do {$_ = shift // q{}; (length) ? $_ : 'default_value'};
    $arg;
    }

print f( )."\n";          # prints "default_value" 
print f( undef )."\n";    # prints "default_value" 
print f( q{} )."\n";      # prints "default_value" 
print f( 0 )."\n";        # prints "0" 
print f( 1 )."\n";        # prints "1" 
print f( 'value' )."\n";  # prints "value"

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I don't want warnings or to duplicate the use of 'default_value'.

Is there a simpler / more elegant solution, say... without a named temporary variable?

A succinct solution which is functional back to earlier perl versions (5.6 or 5.8) would be a plus as well.

As always, your wisdom and opinions are appreciated.

In reply to Assigning default values to function arguments which may be “empty” by Wyrdweaver

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