Who am I? Inheritance question

kwaping has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Who am I? Inheritance question by philcrow (Priest) on Mar 16, 2006 at 21:58 UTC
If the "generic method" you have in mind is a class method it should start something like: `sub generally_useful { my $class = shift; # ... }` [download] That $class will be the invoking class, not necessarily the __PACKAGE__ where generally_useful lives. This works for constructors. If the method is an instance method, it will be more like: `sub instance_meth { my $self = shift; my $class = ref $self; }` [download] Phil Update: Added instance method example.	[reply] [d/l] [select]
Re^2: Who am I? Inheritance question by dragonchild (Archbishop) on Mar 16, 2006 at 22:08 UTC
`sub instance_meth { my $self = shift; my $class = Scalar::Util::blessed $self; }` [download] My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re^3: Who am I? Inheritance question by diotalevi (Canon) on Mar 16, 2006 at 23:26 UTC
Does this still work if you want $self to lie to instance_meth about what class it is? Can a mock object still be passed in here? I know ref() is overrideable but it's painful. How does a person handle that with Scalar::Util::blessed? ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply]
Re^4: Who am I? Inheritance question by dragonchild (Archbishop) on Mar 17, 2006 at 03:30 UTC
Re^5: Who am I? Inheritance question by diotalevi (Canon) on Mar 17, 2006 at 06:09 UTC
Some notes below your chosen depth have not been shown here
Re^5: Who am I? Inheritance question by adrianh (Chancellor) on Mar 17, 2006 at 13:37 UTC
Re: Who am I? Inheritance question by holli (Abbot) on Mar 16, 2006 at 22:15 UTC
If I get you right you want to put code into the superclass that is dependend on it's subclass. This is generally a design flaw. the superclass should know nothing about it's subclasses. If you mean it the other way round, you just need to call isa(CLASS) on the object. holli, /regexed monk/	[reply]
Re: Who am I? Inheritance question by ikegami (Patriarch) on Mar 16, 2006 at 22:35 UTC
How about `if ($user->isa('Client')) { $user->method(); }` [download] or `if ($user->can('method')) { $user->method(); }` [download]	[reply] [d/l] [select]
Re: Who am I? Inheritance question by lima1 (Curate) on Mar 16, 2006 at 22:09 UTC
why do you want this if/else code in User? i think good OO design is when the baseclass does not know anything about its childclasses. you should implement the differences in the child classes. so provide an abstract method in User that the child classes implement. common code can be shared in a private method in user. or generalize your code for the generic method in User so that this method only requires some member variables that can be set in the childs constructors.	[reply]
Re^2: Who am I? Inheritance question by kwaping (Priest) on Mar 16, 2006 at 23:37 UTC
or generalize your code for the generic method in User so that this method only requires some member variables that can be set in the childs constructors. Ah, that might do it, I'll try that. Update: Yep, that did it, thanks! I set `our ($var1,$var2);` in User then set `$User::var1 = 'foo'; $User::var2 = 'bar';` in Client. --- It's all fine and dandy until someone has to look at the code.	[reply] [d/l] [select]