in reply to Refactoring Perl #7 - Remove Assignments to Parameters

even after your update, you probably still want to change the main example in your post ... the initial code black already has the param assigned to a temp variable in the my $arg_ref = shift; line and demonstrates the spirit of the refactoring -- it should be your "post refactoring" example. Your "pre refactoring" example should have every line modifying $_[0] directly.

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Re^2: Refactoring Perl #7 - Remove Assignments to Parameters
by agianni (Hermit) on Aug 24, 2007 at 12:51 UTC
    Actually, I think the example code as it stands is in the spirit if not the word of what the refactoring pattern is meant to avoid. While $arg_ref is a local temp, it's still a reference to the original arguments (a hashref), so updating it would update the arguments pass, which is what this pattern is meant to address. Hence the introduction of the secondary temp. That said, for the sake of completeness, the completely un-refactored code might look like this as you suggest: 
    sub discount{
    $_[0]->{input_val} -= $_[0]->{input_val} > 50 ? 2 : 0;
    $_[0]->{input_val} -= $_[0]->{quantity} > 100 ? 1 : 0;
    $_[0]->{input_val} -= $_[0]->{year_to_date} > 10000 ? 4 : 0;
    return $_[0]->{input_val};
}

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