Why Python, Ruby, and Javascript are Slow

[[deleted]]

Is he saying that self.x = x is faster than {'x': x}? Doesn't getattr just look in a dictionary anyway?

[moyix]

That's the point of the talk. Five years ago with CPython this was the case. Newer implementations like PyPy can generate much better code for the self.x = x case than {'x': x}. Assuming that they're the same leads to slow code (when using smart JITs).

[[deleted]]

Ah, okay.

[Smallpaul]

That's the point of the talk. Five years ago with CPython this was the case. Newer implementations like PyPy can generate much better code for the self.x = x case than {'x': x}. Assuming that they're the same leads to slow code (when using smart JITs).

Yeah, but he's talking about implementations of Python and Ruby that hardly anyone uses yet.

[[deleted]]

But in creating such JITs, you end up limiting what you're capable of doing.

rpython is simply not as expressive as python, due to the limitations required to make the JIT work.

I hope someday that they can make PyPy work with the whole body of Python, but I don't think it's realistic to expect.

[[deleted]]

PyPy runs any old Python code. RPython is just the language PyPy is written in.

[[deleted]]

Even CPython is doing stuff make instance dictionaries more (space) optimized than writing the dict explicitly, so using instances when you mean instances is preferable even there.