On 4/25/2012 5:01 PM, Steven D'Aprano wrote:
On Wed, 25 Apr 2012 13:49:24 -0700, Adam Skutt wrote:
Though, maybe it's better to use a different keyword than 'is' though,
due to the plain English
connotations of the term; I like 'sameobj' personally, for whatever
little it matters. Really, I think taking away the 'is' operator
altogether is better, so the only way to test identity is:
id(x) == id(y)
Four reasons why that's a bad idea:
1) The "is" operator is fast, because it can be implemented directly by
the interpreter as a simple pointer comparison (or equivalent).
This assumes that everything is, internally, an object. In CPython,
that's the case, because Python is a naive interpreter and everything,
including numbers, is "boxed". That's not true of PyPy or Shed Skin.
So does "is" have to force the creation of a temporary boxed object?
The concept of "object" vs. the implementation of objects is
one reason you don't necessarily want to expose the implementation.
John Nagle
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