[Python-3000] Bound and unbound methods (original) (raw)

Guido van Rossum guido at python.org
Wed Aug 16 06:13:11 CEST 2006

On 8/13/06, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

Talin wrote: > the compiler would note the combination of the attribute access and the > call, and combine them into an opcode that skips the whole method > creation step.

Something like that could probably be made to work. You'd want to be careful to do the optimisation only when the attribute in question is an ordinary attribute, not a property or other descriptor. I'm also -1 on eliminating bound methods entirely. I worked through that idea in considerable depth during my discussions with the author of Prothon, which was also to have been without any notion of bound methods. The consequences are further-reaching than you might think at first. The bottom line is that without bound methods, Python wouldn't really be Python any more.

Right. I'm against anything that changes the current semantics. I'm all for a compiler optimization that turns " . ( )" into a single opcode that somehow manages to avoid creating the bound object. As long as it also does the right thing in case the name refers to something that's not quite a standard method -- be it a class method or static method, or a class, or anything else callable (or even not callable :-). And it would be fine if that optimization wasn't used if there are keyword arguments, or *args or **kwds, or more than N arguments for some N > 3 or so.

But, as Thomas says, it was tried before and didn't quite work. Maybe we can borrow some ideas from IronPython, which boasts a 7x faster method call (or was it function call? it was a call anyway); and according to Jim Hugunin only half of that speed-up (on a linear or logarithmic scale? he didn't say) can be explained through the .NET JIT.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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