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Representation of objects
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Date: 2005-08-16 (22:04)
From: Nathaniel Gray <n8gray@g...>
Subject: Representation of objects
I've been poking around a bit into the representation of objects in
OCaml and I'm a bit confused.  Based on caml_get_public_method in
asmrun/obj.c and various bits of stdlib/camlinternalOO.ml I see that
the method table is an "array" where the even entries are closures and
the odd entries "tags" -- hashed method names.  (The first two entries
are special.)  The table is stored sorted in order of increasing tag
value.  Please correct me if I've misunderstood something here.

I've got two questions:

1.  Does this mean that essentially all method invocations need to
search the method table?  The method table of a superclass is no
longer a prefix of that of a subclass.  There's a GETMETHOD(i,obj)
bytecode, but I'm struggling to figure out when you could use it.

2.  What about hash collisions?  There's no collision resolution code
in the method lookup functions.


>>>-- Nathaniel Gray -- Caltech Computer Science ------>
>>>-- Mojave Project -- http://mojave.cs.caltech.edu -->