Matt Nordhoff <[EMAIL PROTECTED]> writes:
> Steven D'Aprano wrote:
>> Except that using has_key() means making an attribute lookup, which takes
>> time.
>
> I was going to say that, but doesn't 'in' require an attribute lookup of
> some sort too, of __contains__ or whatever?
It doesn't. Frequent operations like __contains__ are implemented as
slots in the C struct describing the type. The code that implements
"obj1 in obj2" simply executes something like:
result = obj1->ob_type->tp_contains(obj2); // intentionally simplified
User-defined types (aka new-style classes) contain additional magic
that react to assignment to YourType.__contains__ (typically performed
while the class is being built), to which they react by setting
"tp_contains" to a C wrapper that calls the intended function and
interprets the result.
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