4 ms·

> I think that all the metaprogramming magic that Ruby allows is at odds with speed. I don't think so, Java and C# also have metaprogramming (reflection, class

by laureny 13y ago

> I think that all the metaprogramming magic that Ruby allows is at odds with speed. I don't think so, Java and C# also have metaprogramming (reflection, class loading, bytecode manipulation) and they are still plenty fast. Ruby's liability is that it's dynamically typed, and this puts a hard limit on how fast it can be (and also on how toolable it can be, but that's a separate discussion).

adamnemecek 13y ago
I mean metaprogramming support is kind of a spectrum and neither Java nor C# support it to the same degree as Ruby. For one thing and for another, C# and Java have large corporations supporting those languages which try very hard to make the runtimes fast so it's not a fair comparison.
- pjmlp 13y ago
  Then compare it with compilers for dynamic languages like Lisp, Scheme, Dylan, Smalltalk...
  - adamnemecek 13y ago
    I said tricky, not impossible but I will, even though I'm not sure I'm really qualified to talk about these languages for one thing and for another, I think that these sort of comparisons are pretty pointless to begin with. Also I'm not sure where you are exactly going with your comment. Lisp + Scheme: I mean if nothing else, people have been trying to make them fast for the last more than half of century. Plus AFAIK most Lisp meta-programming code is generated during compile time through macros not during run-time. Dylan: I don't really know anything about Dylan but it seems to have come out of Apple and CMU, so there's that. Plus it seems to be just a Lisp dialect. Smalltalk: You consider Smalltalk fast? Lol.
    - pjmlp 13y ago
      >Smalltalk: You consider Smalltalk fast? Lol. Well, any Smalltalk JIT beat the standard Ruby implementation hands down, what can I say?!
andrewvc 13y ago
Reflection in Java is in fact slow. The difference is that in ruby that stuff is pervasive, in Java you rarely use reflection.
- twerquie 13y ago
  Reflection is also very slow in C#
  - DonnyV 13y ago
    Not it is not. A lot of basic metadata is cached and quickly accessible.
InclinedPlane 13y ago
How much metaprogramming is normally going on behind the scenes in a typical Ruby/Rails app vs Java or C# though? If you do a lot of reflection in Java then you'll end up with some pretty crummy performance, but the average Java program doesn't have much.
- philwelch 13y ago
  It's not just the actual metaprogramming, i.e. define_method is slow. It's also the runtime implications of metaprogramming being possible, i.e. needing to dispatch each and every method call dynamically just in case someone called define_method. Java can turn every method call into a function pointer at compile time.
bronson 13y ago
Metaprogramming is code using define_method (optionally closing over local variables), instance_eval, and stuff of that nature. Even with bytecode manipulation they would be very difficult to emulate in Java/C++ and would be quite slow. That said, JavaScript is not far off of Ruby's monkeying capabilities and yet pretty darned fast.

by laureny 13y ago

adamnemecek 13y ago

I mean metaprogramming support is kind of a spectrum and neither Java nor C# support it to the same degree as Ruby. For one thing and for another, C# and Java have large corporations supporting those languages which try very hard to make the runtimes fast so it's not a fair comparison.

pjmlp 13y ago
Then compare it with compilers for dynamic languages like Lisp, Scheme, Dylan, Smalltalk...
- adamnemecek 13y ago
  I said tricky, not impossible but I will, even though I'm not sure I'm really qualified to talk about these languages for one thing and for another, I think that these sort of comparisons are pretty pointless to begin with. Also I'm not sure where you are exactly going with your comment. Lisp + Scheme: I mean if nothing else, people have been trying to make them fast for the last more than half of century. Plus AFAIK most Lisp meta-programming code is generated during compile time through macros not during run-time. Dylan: I don't really know anything about Dylan but it seems to have come out of Apple and CMU, so there's that. Plus it seems to be just a Lisp dialect. Smalltalk: You consider Smalltalk fast? Lol.
  - pjmlp 13y ago
    >Smalltalk: You consider Smalltalk fast? Lol. Well, any Smalltalk JIT beat the standard Ruby implementation hands down, what can I say?!

andrewvc 13y ago

Reflection in Java is in fact slow. The difference is that in ruby that stuff is pervasive, in Java you rarely use reflection.

twerquie 13y ago
Reflection is also very slow in C#
- DonnyV 13y ago
  Not it is not. A lot of basic metadata is cached and quickly accessible.

InclinedPlane 13y ago

How much metaprogramming is normally going on behind the scenes in a typical Ruby/Rails app vs Java or C# though? If you do a lot of reflection in Java then you'll end up with some pretty crummy performance, but the average Java program doesn't have much.

philwelch 13y ago
It's not just the actual metaprogramming, i.e. define_method is slow. It's also the runtime implications of metaprogramming being possible, i.e. needing to dispatch each and every method call dynamically just in case someone called define_method. Java can turn every method call into a function pointer at compile time.

bronson 13y ago

Metaprogramming is code using define_method (optionally closing over local variables), instance_eval, and stuff of that nature. Even with bytecode manipulation they would be very difficult to emulate in Java/C++ and would be quite slow. That said, JavaScript is not far off of Ruby's monkeying capabilities and yet pretty darned fast.