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Not fully OO ?

Ricardo Aráoz ricaraoz at gmail.com
Mon Sep 22 10:36:18 EDT 2008 
Kay Schluehr wrote:
> On 20 Sep., 23:07, "Aaron \"Castironpi\" Brady" <castiro... at gmail.com>
> wrote:
>> On Sep 20, 3:22 pm, Kay Schluehr <kay.schlu... at gmx.net> wrote:
>>
>>
>>
>>> On 20 Sep., 18:33, Bruno Desthuilliers
>>> <bdesth.quelquech... at free.quelquepart.fr> wrote:
>>>> The following definitions are AFAIK the only commonly accepted
>>>> definitions about OO:
>>>> 1/ an object is defined by identity, state and behaviour
>>>> 2/ objects interacts by sending messages each other
>>>> 3/ an OO program is made of interacting objects
>>>> I let you find out whether Python meets these 3 definitions - and if
>>>> Java does (hint : in Python, everything you can bind to a name is an
>>>> object - this is not true in Java or C++).
>>> This is correct but it detracts from a more general problem of
>>> language "paradigms".
>>> Assume you type
>>>>>> 2+2
>>> 4
>>> Now you are free to interpret this as a simple, primitive arithmetic
>>> operation but you can also claim that 2 sends an __add__ message to 2.
>>> Hereby the state of the 2 objects are not altered but a new 4 object
>>> is created. OO babble is more impressive isn't it?
>>> Actually it is simply wrong in the mentioned case and here is the
>>> proof:
>>> def foo():
>>>     return 2+2
>>> import dis
>>> dis.dis(foo)
>>>   2           0 LOAD_CONST               2 (4)
>>>               3 RETURN_VALUE
>>> OO is a heuristic method used to understand the semantics of a
>>> programming language. It can also inspire language design but as
>>> you've rightly said: jugde yourself and see how far you get with it.
>>> Applying OO on interpreter level is by no means a sign of a high
>>> quality implementation whereas structuring programs in the large will
>>> likely benefit from class based organization and encapsulation. Of
>>> course one can also reverse the value hierarchy and find perverse joy
>>> in having a pure OO language but apply monkey patching everywhere. I
>>> suppose you know which language I'm talking about...
>> It sounds like you think that you -can- write OO programs in Python,
>> but you don't have to.  I agree.
> 
> The whole point of OO is providing high level ( system level ) not low
> level ( interpreter level ) semantics. Partitioning a system into
> isolated and communicating objects is a strong and important metaphor.
> Recently there were some comments on the web that mentioned Erlang to
> be pretty much OO in this respect although Erlang is functional and
> has no base level notion of an "object". It's even well known that Joe
> Armstrong holds low opinions about the entire object business.
> 
> Notice that I believe that the popular meme that OO is "bolted on"
> Python has little if nothing to do with OO itself but with API
> consistency. When people have to type len(x) instead of x.len() this
> breaks their expectations on how the language has to behave.

x.__len__()
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