Hello all,

I am using flyweight objects (i.e. the objects are blessed scalars which are keys of a lexical hash), which have resource-intensive methods that don't take any arguments.

I sometimes have a way to get pre-computed values for many of these methods.

I want to do two things :

1. Be able to tell the objects what the return values for these methods should be, so that the methods don't have to be called sometimes.
2. Memoize any calls to these methods (on an instance level), so that the methods don't do the resource-intensive operations multiple times.

The way I've done this is as follows (_get, _set, and _is_set are methods that get, set or check the attribute of the object by looking in the lexical hash) :

# In the various classes :
__PACKAGE__->setupMemoizedSubs(
   methodname => sub { 
                 my $self = shift; 
                 #... do resource-intensive stuff .. },
   anothermethod => sub { ... },
)

# In a common base class :
sub setupMemoizedSubs {
    my ($class,%args) = @_;
    no strict 'refs';
    while (my ($name,$sub) = each %args) {
        my $private_element = "__memoized_$name";
        *{"${class}::$name"} = sub {
             my $self = shift;
             $self->_set($private_element => $_[0]) if @_==1;
             return $self->_get($private_element)
               if $self->_is_set($private_element);
             $self->_set($private_element => $sub->($self)); 
             $self->_get($private_element);
        };
    }
    use strict 'refs';
}

# Somewhere else
$object->methodname("pre-computed value"); # set the value
$object->methodname();  # Gets the value we set

# Or if we omit the first one...
$object->methodname()  # Actually calls the method
[download]

So, my questions are :

• Does it matter whether I do this with an anonymous sub in a closure (as above) or is a dummy named subroutine better? -
• Could I have done the above using Memoize.pm somehow?
• Any other suggested methods for accomplishing this?

thanks

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