Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano steven at
Wed Nov 12 04:14:00 CET 2008

On Wed, 12 Nov 2008 02:44:42 +0000, Steven D'Aprano wrote:

> But one thing is clear: values aren't references. Given the assignment
> x=1, the value of x is not "a reference to 1" but 1 itself. So the one
> thing we can unambiguously say is that Algol's assignment model is not
> the same as Python's assignment model.

Sorry, this is very misleading.

What I meant to say is that if you are one of those people who insist 
that values in Python are references, then Algol's assignment model is 
not that same as what you understand Python assignment to be.

I am very happy to say that x=1 implies that the value of x is the object 
1 itself, in fact I would insist on such a definition of value.

If you insist that Python is call by value, the only way that can work is 
by defining values to be references, which is nothing like Algol.


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