in reply to only allow certain parameters
I assume you want to set the value if a parameter is passed or if the current value is undef, and just return the current value otherwise:
I would also define your %valid_params outside of the subroutine. No need to define them each time you call the sub. Also if you want to nano-optimize your code, consider using exists to see if the key exists in valid_params instead of testing its value, like so:sub balance_by { my $self = shift; my %valid_params = map {$_ => 1} ('foo', 'bar'); if (@_ or ! defined $self->{'balance_by'}) { my $entry = shift; $self->{'balance_by'} = (defined $entry and $valid_params{$entry}) ? $entry : 'foo'; } return $self->{'balance_by'}; }
Also, unless I'm mistaken, there doesn't seem to be any reason to not default your fields in the 'new' method...(unless you just wanted 'if (@_)...' in that conditional?)my %valid_params; undef @valid_params{qw(foo bar)}; ... (defined $entry and exists $valid_params{$entry}) ...
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