Re: dictionary as property

[Benjamin Niemann]

Thanos Tsouanas wrote:

 Hello.
 
 (How) can I have a class property d, such that d['foo'] = 'bar' will run
 a certain function of the class with 'foo' and 'bar' as it's arguments?

I think you mean:

class A:
  def __init__(self):
self.d = {}

  def dict_change(self, key, value):
print key, value

a = A()
a.d['foo'] = 'bar'
-- foo bar

'a' only has a reference to 'd', it won't know, who has a copy of this
reference and what done to it.
What you could create, is a wrapper around 'd', that passes __getitem__,
__setitem__ and every other required method to the underlying dict and call
the appropriate hook method of A

class WrappedDict:
  def __init__(self, owner, d):
self.owner = owner
self.d = d

  def __setitem__(self, key, value):
self.owner.dict_changed(key, value)
self.d[key] = value

  def __getitem(self, key):
return self.d[key]

  

And in A.__init__
  self.d = WrappedDict(self, {})

You may also subclass WrappedDict from dict...

-- 
Benjamin Niemann
Email: pink at odahoda dot de
WWW: http://www.odahoda.de/
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dictionary as property

[Thanos Tsouanas]

Hello.

(How) can I have a class property d, such that d['foo'] = 'bar' will run
a certain function of the class with 'foo' and 'bar' as it's arguments?

Thanks in advance.

-- 
Thanos Tsouanas  .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/
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Re: dictionary as property

[Gerhard Haering]

On Tue, Jul 19, 2005 at 07:56:20PM +0300, Thanos Tsouanas wrote:
 Hello.
 
 (How) can I have a class property d, such that d['foo'] = 'bar' will run
 a certain function of the class with 'foo' and 'bar' as it's arguments?

You could implement a custom container type that will do what you want.
See http://docs.python.org/ref/sequence-types.html for __setitem__.

Quick hack:

 class Foo:
... def __init__(self):
... self.d = self
... def __setitem__(self, key, value):
... getattr(self, key)(value)
... def bar(self, param):
... print bar got called with, param
...
 foo = Foo()
 foo.d[bar] = 42
bar got called with 42


-- Gerhard
-- 
Gerhard Häring - [EMAIL PROTECTED] - Python, web  database development


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Re: dictionary as property

[Thanos Tsouanas]

On Tue, Jul 19, 2005 at 07:00:10PM +0200, Gerhard Haering wrote:
 On Tue, Jul 19, 2005 at 07:56:20PM +0300, Thanos Tsouanas wrote:
  Hello.
  
  (How) can I have a class property d, such that d['foo'] = 'bar' will run
  a certain function of the class with 'foo' and 'bar' as it's arguments?
 
 You could implement a custom container type that will do what you want.
 See http://docs.python.org/ref/sequence-types.html for __setitem__.

Thanks, that doc had all I needed :)

-- 
Thanos Tsouanas  .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/
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