why function got dictionary

[AlFire]

Hi,

I am seeking an explanation for following:

Python 2.5.2 (r252:60911, Apr  8 2008, 21:49:41)
[GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> def g(): return
...
 >>> g.__dict__
{}

Q: why function got dictionary? What it is used for?


Thx, Andy
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Re: why function got dictionary

[AlFire]

Diez B. Roggisch wrote:
>>
>> Q: why function got dictionary? What it is used for?
> 
> because it is an object, and you can do e.g.
> 

you mean an object in the following sense?

 >>>  isinstance(g,object)
True


where could I read more about that?

Andy
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why objects of old style classes are instances of 'object'

[AlFire]

Hi,

Q: from the subject, why objects of old style classes are instances of 
'object'?

 >>> class a():pass
 >>> A=a()
 >>> isinstance(A,object)

True



I would expect False


Thx,
Andy
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Re: why objects of old style classes are instances of 'object'

[AlFire]

Diez B. Roggisch wrote:



But not everything is a newstyle-class:


class Foo: pass

...

isinstance(Foo, object)

True

isinstance(Foo, type)

False



class Bar(object): pass

...

isinstance(Bar, type)

True






thx for explanation. but more I look at it less and less I like the 
notation of new-style-class definition. what is an added value of adding 
"(object)" since it is already an object. Any insight?


Note: I am not a language purist, more a pragmatic who like a good style.

Andy
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Re: Python Success stories

[AlFire]

Cristina Yenyxe González García wrote:

2008/4/23, Reedick, Andrew <[EMAIL PROTECTED]>:

IIRC, Python is used in games like Eve Online (SciFi MMO) and Vampire:
 Bloodlines (RPG.)  Years later, a dedicated fan is still fixing/updating
 the Bloodlines python scripts that control the dialogue and scripted
 events.



Now that you mention it, Python was also used in the Star Wars:
Knights of the Old Republic (KotOR) saga. You can even search the
scripts across the disc and take a look at hilarious code comments
like "this works but I don't know why" :D


and Shrek 3 http://www.linuxjournal.com/article/9653

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a.
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Re: Python Success stories

[AlFire]

Bob Woodham wrote:



x = x++;

has unspecified behaviour in C.


what about C++
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is +=1 thread safe

[AlFire]

Hi,

I have a piece of software which uses threads in very massive way - like 
hundreds of  them generated every second.


there is also a piece of code which maintains the number of outstanding 
threads, simply


counter+=1 is executed when before starting the thread and counter-=1 
after it finishes.


all is very simple and by the end of the program life I expect the 
counter to zero out.


however I am getting values -1, -2, 1 ,2 ,3 and quite often 0 as expected.

I guarded those statement with Lock.{acquire,release} and now it always 
returns 0.



But I still can not believe that +=1 is not a thread safe operation.


Any clue?

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Andy
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Re: is +=1 thread safe

[AlFire]

Duncan Booth wrote:
[...]


is equivalent to:

  x = x.__iadd__(1)


thx all for answers and hints ...



Generating hundreds of threads is, BTW, a very good way to get poor 
performance on any system. Don't do that. Create a few threads and put the 
actions for those threads into a Queue. If you want the threads to execute 
in parallel investigate using sub-processes.



I know that limitation. However I am bridging to existing software which 
is hard to be changed. and on powerful machine I have at hand it works 
quite fast.




The threading module already has a function to return the number of Thread 
objects currently alive.


I have threads within threads - so it does not suit me :-(.

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Andy
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Re: is +=1 thread safe

[AlFire]

Alexander Schmolck wrote:

AlFire <[EMAIL PROTECTED]> writes:


The threading module already has a function to return the number of Thread
objects currently alive.

I have threads within threads - so it does not suit me :-(.


How about using a scalar numpy array? They are mutable, so I assume that x +=
1 should be atomic.


I ended up with following:

counter=[]  counter=0

counter.append(None)counter+=1

counter.pop()   counter-=1

len(counter)counter

A.
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