Re: Dynamic Typing Efficiency

In Python a value would have a pointer to a dictionary with members like
__add__, __sub__, etc. (try dir(0)) which would be called to do the
appropriate operations. So, for example, 5+5 is equivalent to x.__add__(y).
This also allows the methods to be overloaded by the user to add new types
to the language.


Lua does something very similar and is much simpler (faster?) than Python.
See "The Implementation of Lua 5.0":


http://www.tecgraf.puc-rio.br/~lhf/ftp/doc/sblp2005.pdf


You might consider an array of function pointers, indexed by the op-code,
rather than using a switch/case statement. You may also consider having
different op-codes for built-in types (IADD, FADD, etc.).


Another trick is for the "type" of a value to be a pointer to a static type
descriptor rather than a special number. That way there is no possibility
of number clashes and reflection is much easier.


Luke McCarthy

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