read-only attributes

[john peter]

Thank you for the suggestion!

bruno at modulix <onurb at xiludom.gro> wrote:  limodou wrote:
> On 2/10/06, john peter  wrote:
(snip)

>> what do i have to do if i want my application code to have
>>read-only
>> attributes?
>>
> I think you may consider property() built-in function:
> 
> property( [fget[, fset[, fdel[, doc]]]])
> 
> Return a property attribute for new-style classes (classes that derive
> from object).
> fget is a function

s/function/callable/

> for getting an attribute value, likewise fset is a
> function for setting, and fdel a function for del'ing, an attribute.
> Typical use is to define a managed attribute x:
> 
> 
> class C(object):
>     def __init__(self): self.__x = None
>     def getx(self): return self.__x
>     def setx(self, value): self.__x = value
>     def delx(self): del self.__x
>     x = property(getx, setx, delx, "I'm the 'x' property.")

Note that you don't need to define all three accessors. For a
'read-only' attribute, just define the getter:

class ReadOnly(object):
   def __init__(self, x):
      self._x = x
   x = property(fget=lambda self: self._x)

-- 
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb at xiludom.gro'.split('@')])"
-- 
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