If your perl object is large and the blessed hash has many members does it makes sense to store the value of a hash lookup in a my variable for further usage to save the lookup time. Or is this unnessary micro optimization?

eq.  This:

sub sub do_somn {
    my $self = shift;
    my $username = $self->{username};

    my $a = $username; # for some reason
    my $b = $username; # for some other reason.
    ...
}

 Verse this:

sub do_somn {
    my $self = shift;

    my $a = $self->{username}; # for some reason
    my $b = $self->{username}; # for some other reason.
    ...
}

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In reply to Should we bother to save hash lookups for performance? by dlink

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