7 ms·

That's pretty central to any OO language. "Everything's an object." Veering away from that, only serves to turn the language into a mess of boxing and unboxing.

by stuki 12y ago

That's pretty central to any OO language. "Everything's an object." Veering away from that, only serves to turn the language into a mess of boxing and unboxing. That's not to say that OO is necessarily the ideal language paradigm, but it has certainly been the most dominant in the era Python has existed.

theseoafs 12y ago
OO languages do not have to do this. Ruby doesn't, for instance (that is, it turns the language into a "mess of boxing and unboxing", but that's invisible to the programmer and makes working with integers so much more efficient). There's simply no reason to allocate integers on the heap -- it's a bad design desicion.
- icebraining 12y ago
  How does Ruby know that 'a' is an integer and not any other type? Java and C# can use the variable types to track this, but I don't see how would a dynamic language work without tagging the value.
  - gregwebs 12y ago
    My understanding from 5 years ago is that in MRI the leading bit is reserved to indicate whether something is an integer. This of course reduces the size of numbers that fit into a machine word but it seems like a pretty good tradeoff.
    - lispm 12y ago
      Most Lisp systems use tags. Several data types will have tags included in the data word, like fixnums, characters. Other data types have an extra word.
    - icebraining 12y ago
      Yeah, apparently they're called tagged pointers. The More You Know. EDIT: And here's Guido explaining why he didn't want that in Python: https://mail.python.org/pipermail/python-dev/2004-July/046147.html https://mail.python.org/pipermail/python-dev/2004-July/04614...
  - mantrax5 12y ago
    One easy way to know is to run it a few times and observe the behavior. This is why JIT runtimes need a "warm up time" to get really fast, say V8 for JavaScript.
  - dragonwriter 12y ago
    Ruby -- or more precisely, MRI, though some other interpretations may do something similar -- uses the a fixed set of object_ids (which is what is stored on the stack to locate an object on the heap) for small integers, so if the object_id is within that range, the interpreter uses it directly to calculate the value, and doesn't need to go to the heap to get a value. (MRI does a similar thing with the values nil, true, and false, as well.)
    - ForHackernews 12y ago
      Python does the same thing for integers in the range (-5, 256)
- ForHackernews 12y ago
  Python statically allocates small integers (-5 to 256), so you're not actually creating a new object unless you're creating one outside that range. http://www.laurentluce.com/posts/python-integer-objects-implementation/ http://www.laurentluce.com/posts/python-integer-objects-impl...
  - theseoafs 12y ago
    Dynamic allocation isn't the only cost there -- a cost that's just as big when you're doing number crunching in Python is cache efficiency. If every number is on the heap, and every number in Python is ~20 bytes long, you're going to have caching problems, even if your numbers only ever range from -5 to 256.

by stuki 12y ago

theseoafs 12y ago

OO languages do not have to do this. Ruby doesn't, for instance (that is, it turns the language into a "mess of boxing and unboxing", but that's invisible to the programmer and makes working with integers so much more efficient). There's simply no reason to allocate integers on the heap -- it's a bad design desicion.

icebraining 12y ago
How does Ruby know that 'a' is an integer and not any other type? Java and C# can use the variable types to track this, but I don't see how would a dynamic language work without tagging the value.
- gregwebs 12y ago
  My understanding from 5 years ago is that in MRI the leading bit is reserved to indicate whether something is an integer. This of course reduces the size of numbers that fit into a machine word but it seems like a pretty good tradeoff.
  - lispm 12y ago
    Most Lisp systems use tags. Several data types will have tags included in the data word, like fixnums, characters. Other data types have an extra word.
  - icebraining 12y ago
    Yeah, apparently they're called tagged pointers. The More You Know. EDIT: And here's Guido explaining why he didn't want that in Python: https://mail.python.org/pipermail/python-dev/2004-July/046147.html https://mail.python.org/pipermail/python-dev/2004-July/04614...
- mantrax5 12y ago
  One easy way to know is to run it a few times and observe the behavior. This is why JIT runtimes need a "warm up time" to get really fast, say V8 for JavaScript.
- dragonwriter 12y ago
  Ruby -- or more precisely, MRI, though some other interpretations may do something similar -- uses the a fixed set of object_ids (which is what is stored on the stack to locate an object on the heap) for small integers, so if the object_id is within that range, the interpreter uses it directly to calculate the value, and doesn't need to go to the heap to get a value. (MRI does a similar thing with the values nil, true, and false, as well.)
  - ForHackernews 12y ago
    Python does the same thing for integers in the range (-5, 256)
ForHackernews 12y ago
Python statically allocates small integers (-5 to 256), so you're not actually creating a new object unless you're creating one outside that range. http://www.laurentluce.com/posts/python-integer-objects-implementation/ http://www.laurentluce.com/posts/python-integer-objects-impl...
- theseoafs 12y ago
  Dynamic allocation isn't the only cost there -- a cost that's just as big when you're doing number crunching in Python is cache efficiency. If every number is on the heap, and every number in Python is ~20 bytes long, you're going to have caching problems, even if your numbers only ever range from -5 to 256.