[SearchBuilder-devel] problems with capitalization.pm and OO modules

David Glasser glasser at bestpractical.com
Tue Jun 14 15:02:37 EDT 2005

capitalization.pm is fundamentally incompatible with OO modules.

Given a class such as SearchBuilder, the lower-case methods are  
aliased to the uppercase methods.

However, when you subclass SearchBuilder, you run into problems.   
Let's say you want to override SomeFunction.  There are a few choices:

(a) Define SubClass::SomeFunction.  But then if you use - 
 >some_function in your code anywhere, it won't find  
SubClass::SomeFunction -- it'll call SearchBuilder::some_function,  
which is aliased to SearchBuilder::SomeFunction.

(b) Define SubClass::some_function.  But then if you use - 
 >SomeFunction in your code anywhere, or in fact wherever  
SearchBuilder.pm *itself* uses ->SomeFunction, it won't find  
SubClass::some_function -- it'll call SearchBuilder::SomeFunction.

(c) Require every subclass of SearchBuilder to define the methods  
that they override as CamelCase, and to also use capitalization to  
lower_case all functions that they override.  But in this case:
    * capitalization is no longer the optional feature that we  
advertise it as -- anybody who ever wants to make a subclass **must**  
follow this rule
    * it requires subclassers to use CamelCase, which kind of defeats  
the point of allowing customizable casing

For example, I wouldn't be surprised if there are bugs with using  
lower_case method names when addressing a  
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Attached is a tarball showing this problem; just run test.pl to see  
what's going on.

Any ideas?

I've tried the relatively obvious thing which aliases the new_name to
   sub { my $self = shift; $self->$CamelName(@_) }
While this at least fixes the problem of "I overrode it with  
CamelCase and I called it with lower_case and it didn't work", it  
doesn't fix the opposite problem.  There might also be some  
complicated ugly AUTOLOAD-based way to deal with this, but I'm not  
sure what that would be.  Or perhaps you could do something involving  
actually asking SB for one API or the other when you use it?  So you  
might do

   use MySBSubclass qw/:lower_case/;

and the import function would decapitalize MySBSubclass and all of  
its superclass' methods right then?

   Code Monkey, Best Practical Solutions
David Glasser | glasser at bestpractical.com

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