The RTTI module

[Fredrick Paul Eisele <ph...@netarx.com>]

The RTTI module is our first cut at exposing a C++ capability into the Perl 
environment.
RTTI, run time type information, implements serveral type/class functions.

dynamic_cast: can cast from a polymorphic base class to a derived or 
sibling class.  This is implemented as a restricted bless.  I should not be 
allowed to bless into a class for which certain methods will not be supported.

typeid: returns the class to which an object belongs, i.e. the ref function.

actual_cast: bless an object into the most specific class to which it belongs.
The relevance in Xerces is to provide a means for selectively blessing a
DOM::Node into, for example, the DOM::Element class, according to its 
saved type.  It happens that a DOM::Node carries its specific class, the 
object is blessed into this class, upon calling actual_cast.

schema_cast: (in development) when an XML serialization is parsed it 
would be nice if the resulting DOM were blessed into a class.
This could be implemented by reading a URN (namespace?), loading the
appropriate module and blessing the DOM into the package.
i.e. <xyz xmlns="urn:xerces:foo/bar"> would use XML::Xerces::foo::bar;

It is likely that introducing a module to perform these behaviors was ill
conceived and should be rethought.  I frequently use the actual_cast method,
which could easily be added to the Xerces.pm without the need for any RTTI.pm.

-- 
Fredrick Paul Eisele
30910 Telegraph Rd.
Bingham Farms, MI
1.248.647.9800

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