in reply to Re^2: Class::Accessor and Damian's PBP
in thread Class::Accessor and Damian's PBP

Whenever your setter needs to be normalized to a different value lvalue accessors don't cut it.
Well...that certainly used to be the case. Indeed, the fact that you have to employ the complexities of tied proxy variables to retain control when using lvalue accessors, is precisely why I cautioned against lvalue accessors in "Perl Best Practices".

But last week I released the latest version of the Contextual::Return module, with which you can now hide all the complexity of tied proxies behind two simple LVALUE, and RVALUE blocks. For example:

use Contextual::Return; # Name method offers unconstrained access... sub name : lvalue { my ($self) = @_; $name_of{ident $self}; } # Rank method constrains access: can assign only valid ranks # (value being assigned is passed as $_ to LVALUE block)... sub rank : lvalue { my ($self) = @_; LVALUE { croak "Invalid rank ($_) assigned" if !$is_valid_rank{$_}; $rank_of{ident $self} = $_; } RVALUE { $rank_of{ident $self}; } } # Serial method offers read-only access... sub serial { my ($self) = @_; return $snum_of{ident $self}; }

With this functionality now available, I'm seriously reconsidering my long-held objections to lvalue accessors.


Replies are listed 'Best First'.
Re^4: Class::Accessor and Damian's PBP
by nothingmuch (Priest) on Feb 26, 2006 at 06:52 UTC
    Wow, that's pretty nice... Great work =)

    zz zZ Z Z #!perl