retard, el 1 de diciembre a las 11:42 me escribiste: > Tue, 01 Dec 2009 03:13:28 -0800, Walter Bright wrote: > > > retard wrote: > >> Overall these simplifications don't remove any crucial high level > >> language features, in fact they make the code simpler and shorter. For > >> instance there isn't high level code that can only be written with > >> 8-bit byte primitives, static methods or closures, but not with 32-bit > >> generic ints, singletons, and generic higher order functions. The only > >> thing you lose is some type safety and efficiency. > > > > I'm no expert on Python, but there are some things one gives up with it: > > > > 1. the ability to do functional style programming. The lack of > > immutability makes for very hard multithreaded programming. > > Even if the language doesn't enforce immutability it's indeed possible to > use immutable data types in a language without pure/const/final > attributes.
And BTW, Python *have* some built-in immutable types (strings, tuples, integers, floats, frozensets, and I don't remember if there is anything else). Python uses convention over hard-discipline (no public/private for example), so you can make your own immutable types, just don't add mutating methods and don't mess with. I agree it's arguable, but people actually use this conventions (they are all consenting adults :), so things works. I can only speak from experience, and my bug count in Python is extremely low, even when doing MT (the Queue module provides a very easy way to pass messages from one thread to another). I agree that, when you don't care much for performance, things are much easier :) > > 2. as you mentioned, there's the performance problem. It's fine if you > > don't need performance, but once you do, the complexity abruptly goes > > way up. > > In D, there's the simplicity problem. It's fine if you don't need > readability, but once you do, the efficiency abruptly goes way down. > > > > > 3. no contract programming (it's very hard to emulate contract > > inheritance) > > True, this is a commonly overlooked feature. I don't know any other > languages than Eiffel or D that support this. > > I'm not sure how hard it would be to emulate this feature in languages > where you can define your own class mechanism. There are libraries to do contracts in Python: http://www.wayforward.net/pycontract/ http://blitiri.com.ar/git/?p=pymisc;a=blob;f=contract.py;h=0d78aa3dc9f3af5336c8d34ce521815ebd7d5ea0;hb=HEAD I don't know if they handle contract inheritance though. There is a PEP for that too: http://www.python.org/dev/peps/pep-0316/ But I don't many people really wants DbC in Python, so I don't think it would be implemented. > > 4. no metaprogramming > > Dynamic languages support dynamic metaprogramming. Ever heard of e.g. > lisp macros? Exactly! You can even generate code dynamically! This is a very nice example: http://code.activestate.com/recipes/362305/ It makes "self" implicit in *pure Python*. If you say dynamic languages don't have metaprogramming capabilities, you just don't have any idea of what a dynamic language really is. > > 5. simple interfacing to C > > In case you mean no unnecessary wrappers etc., this has more to do with > the execution model than language features. Most scripting languages are > interpreted, and require some sort of assistance from the runtime system. > If the language was compiled instead, they wouldn't necessarily need > those. In D you need interfacing code too, it can be a little simpler, that's true. > > 6. scope guard (transactional processing); Python has the miserable > > try-catch-finally paradigm WRONG! See the with statement: http://www.python.org/dev/peps/pep-0343/ with lock: some_non_mt_function() with transaction: some_queries() with file(fname) as f: x = f.read(10) f.write(x) > > 8. RAII > > Ok. > > I think this could also be enforced dynamically. Again, the with statement. > > > > 9. versioning > > I don't know why this can't be done dynamically. It can, and it's pretty common, you can do things like this: class A: if WHATEVER: def __init__(self): pass else: def __init__(self, x): pass > > 10. ability to manage resources directly What do you mean by resource? > > 11. inline assembler You can do bytecode manipulation, which is the assembler of dynamic languages :) I really think the *only* *major* advantage of D over Python is speed. That's it. -- Leandro Lucarella (AKA luca) http://llucax.com.ar/ ---------------------------------------------------------------------- GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145 104C 949E BFB6 5F5A 8D05) ---------------------------------------------------------------------- Cuando el Mártir estaba siendo perseguido y aglutinado por los citronetos, aquellos perversos que pretendian, en su maldad, piononizar las enseñanzas de Peperino. -- Peperino Pómoro
