On Fri, 13 Apr 2007 13:39:08 +0200, Bert Freudenberg wrote:
On Apr 13, 2007, at 13:27 , Klaus D. Witzel wrote:
Hi Bert,
on Thu, 12 Apr 2007 18:31:55 +0200, you wrote:
This is actually wrong.
:)
Only SmallIntegers are special [*].
What happens is this: When you add two SmallIntegers (like "3 + 4"),
and the result is a SmallInteger, the result is calculated in the
bytecode directly. Otherwise, a regular send of #+ is performed.
Right.
From there, everything else happens in the image,
Not really. (Integer>>#+ aNumber) sends (self digitAdd: aNumber) which
is implemented as <primitive: 'primDigitAdd' module: 'LargeIntegers'>
which is part of the VM. Of course the LargeIntegers module may be
absent, have failed to load, may not like the argument, etc.
No, this is an *optional* primitive. It's there purely to speed up
computation and can be safely removed.
Sure, but this thread is not about what happens when the optional
primitive is removed, and I was not reflecting that, either. I was rather
discussing the point when the primitive does *not* fail on one of
Patrick's subclasses and, what the returned species is.
You could change the Integer classes to handle subclasses properly (via
species etc.). So far, this has not been necessary. My point was that
this (unlike SmallIntegers) is *not* hard-coded in the VM.
I think it depends on operand order. When the LargeIntegers module is
invoked (in my previous example when sending + myLargeInteger to
SmallInteger 1) then a "hard-coded" instance of LargePositiveIntegers is
returned.
The attached class can be used (together with my previous example) to
illustrate my point. The class does not inherit from some default large
integer class and the primitive does not fail, regardless of operand
order. I hope I didn't base my argument on a bug or mistake.
FWIW I do not disagree with anything about your argument, except a bit
with "hard-coded".
- Bert -
MyPositiveInteger.st
Description: Binary data
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