Re: copying classes?

2004-12-31 Thread harold fellermann 
On 30.12.2004, at 01:24, It's me wrote:
I would not think that a generic deepcopy would work for all cases.   
An
object can be as simple as a number, for instance, but can also be as
complex as the universe.  I can't imagine anybody would know how to 
copy a
complex object otherthen the object itself.

I always think that a well designed object should have a copyme method.
:=)
take a look at the __setstate__ and __getstate__ documentation of copy
(e.g. pickle) -- with them you can customize the copying task. Anyway,
they work only on instance but not on class objects :(
- harold -
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Re: copying classes?

2004-12-31 Thread Alex Martelli 
harold fellermann [EMAIL PROTECTED] wrote:
   ...
  I always think that a well designed object should have a copyme method.
  :=)

That would be __copy__ or __deepcopy__, but the __getstate__ /
__setstate__ approach is often preferable.

 take a look at the __setstate__ and __getstate__ documentation of copy
 (e.g. pickle) -- with them you can customize the copying task. Anyway,
 they work only on instance but not on class objects :(

They should, if you put them in the class of the class -- the metaclass.

 class mec(type):
...   def __copy__(cls):
... return mec('copyof'+cls.__name__, cls.__bases__,
dict(vars(cls)))
... 
 class foo:
...   __metaclass__ = mec
... 
 bar = copy.copy(foo)
 bar.__name__
'copyoffoo'
 


Alex
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Re: copying classes?

2004-12-30 Thread Hans Nowak 
Jeff Epler wrote:
Here's an example of attempting to deepcopy a class:
class X: pass
... 

import copy
X is copy.deepcopy(X)
Traceback (most recent call last):
  File stdin, line 1, in ?
  File /usr/lib/python2.2/copy.py, line 179, in deepcopy
raise error, \
copy.Error: un-deep-copyable object of type type 'class'
Weird.  I get (Python 2.3.4):
 class X: pass
...
 import copy
 X is copy.deepcopy(X)
True
However:
 class Foo:
... def bar(self, x, y, z): pass
...
 import copy
 FooCopy = copy.deepcopy(Foo)
 FooCopy
class __main__.Foo at 0x0142FE70
 Foo
class __main__.Foo at 0x0142FE70
It appears it doesn't copy the class at all, you just get the same class 
back.

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Hans Nowak
http://zephyrfalcon.org/
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copying classes?

2004-12-29 Thread harold fellermann 
Hi all,
In the documentation of module 'copy' it is said that This version 
does not copy types like module, class, function, method, stack trace, 
stack frame, file, socket, window, array, or any similar types.

Does anyone know another way to (deep)copy objects of type class? What 
is special about the objects of these types that they cannot be easily 
copied?

Any help appreciated,
- harold -
--
I like pigs. Dogs look up to us. Cats look down to us.
Pigs treat us as equal.
-- Winston Churchill
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Re: copying classes?

2004-12-29 Thread Bob Van Zant 
copy.deepcopy() should do the trick. This URL answers a little bit of
your question about the difficulties in copying complex data
structures.

http://pydoc.org/2.3/copy.html

-Bob

On Wed, 2004-12-29 at 19:29 +0100, harold fellermann wrote:
 Hi all,
 
 In the documentation of module 'copy' it is said that This version 
 does not copy types like module, class, function, method, stack trace, 
 stack frame, file, socket, window, array, or any similar types.
 
 Does anyone know another way to (deep)copy objects of type class? What 
 is special about the objects of these types that they cannot be easily 
 copied?
 
 Any help appreciated,
 
 - harold -
 
 
 --
 I like pigs. Dogs look up to us. Cats look down to us.
 Pigs treat us as equal.
 -- Winston Churchill
 

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Re: copying classes?

2004-12-29 Thread Bob Van Zant 
Ha. I just read down to the bottom of pyDoc page.

This version does not copy types like module, class, function, method,
nor stack trace, stack frame, nor file, socket, window, nor array, nor
any similar types.

However, I actually tried it and it worked at least in the simple case:
 class x:
...   def __init__(self):
... self.y = 1
...
 obj = x()
 obj.y
1

 import copy
 z = copy.deepcopy(obj)
 z.y
1
 obj.y = 4
 obj.y
4
 z = copy.deepcopy(obj)
 z.y
4

-Bob

On Wed, 2004-12-29 at 10:42 -0800, Bob Van Zant wrote:
 copy.deepcopy() should do the trick. This URL answers a little bit of
 your question about the difficulties in copying complex data
 structures.
 
 http://pydoc.org/2.3/copy.html
 
 -Bob
 
 On Wed, 2004-12-29 at 19:29 +0100, harold fellermann wrote:
  Hi all,
  
  In the documentation of module 'copy' it is said that This version 
  does not copy types like module, class, function, method, stack trace, 
  stack frame, file, socket, window, array, or any similar types.
  
  Does anyone know another way to (deep)copy objects of type class? What 
  is special about the objects of these types that they cannot be easily 
  copied?
  
  Any help appreciated,
  
  - harold -
  
  
  --
  I like pigs. Dogs look up to us. Cats look down to us.
  Pigs treat us as equal.
  -- Winston Churchill
  
 

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Re: copying classes?

2004-12-29 Thread Jeff Epler 
You copied an instance, not a class.

Here's an example of attempting to deepcopy a class:
 class X: pass
... 
 import copy
 X is copy.deepcopy(X)
Traceback (most recent call last):
  File stdin, line 1, in ?
  File /usr/lib/python2.2/copy.py, line 179, in deepcopy
raise error, \
copy.Error: un-deep-copyable object of type type 'class'

In theory, one could provide a metaclass that allows copying of
instances of that metaclass.  I'll leave this as an exercise to the
reader.

Jeff


pgpjJrXN93ruF.pgp
Description: PGP signature
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Re: copying classes?

2004-12-29 Thread It's me 
I would not think that a generic deepcopy would work for all cases.   An
object can be as simple as a number, for instance, but can also be as
complex as the universe.  I can't imagine anybody would know how to copy a
complex object otherthen the object itself.

I always think that a well designed object should have a copyme method.
:=)

Bob Van Zant [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
 Ha. I just read down to the bottom of pyDoc page.

 This version does not copy types like module, class, function, method,
 nor stack trace, stack frame, nor file, socket, window, nor array, nor
 any similar types.

 However, I actually tried it and it worked at least in the simple case:
  class x:
 ...   def __init__(self):
 ... self.y = 1
 ...
  obj = x()
  obj.y
 1
 
  import copy
  z = copy.deepcopy(obj)
  z.y
 1
  obj.y = 4
  obj.y
 4
  z = copy.deepcopy(obj)
  z.y
 4

 -Bob

 On Wed, 2004-12-29 at 10:42 -0800, Bob Van Zant wrote:
  copy.deepcopy() should do the trick. This URL answers a little bit of
  your question about the difficulties in copying complex data
  structures.
 
  http://pydoc.org/2.3/copy.html
 
  -Bob
 
  On Wed, 2004-12-29 at 19:29 +0100, harold fellermann wrote:
   Hi all,
  
   In the documentation of module 'copy' it is said that This version
   does not copy types like module, class, function, method, stack trace,
   stack frame, file, socket, window, array, or any similar types.
  
   Does anyone know another way to (deep)copy objects of type class? What
   is special about the objects of these types that they cannot be easily
   copied?
  
   Any help appreciated,
  
   - harold -
  
  
   --
   I like pigs. Dogs look up to us. Cats look down to us.
   Pigs treat us as equal.
   -- Winston Churchill
  
 



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