Tkinter callback arguments

[Diez B. Roggisch]

Alf P. Steinbach wrote:

> * Peter Otten:
>> Alf P. Steinbach wrote:
>> 
>>>>     for x in range(0,3):
>>>>         Button(......, command=lambda x=x: function(x))
>>> An alternative reusable alternative is to create a button-with-id class.
>>>
>>> This is my very first Python class so I'm guessing that there are all
>>> sorts of issues, in particular naming conventions.
>> 
>> Pseudo-private attributes
> 
> That means there is some way of making attributes private?

No, it means that in Python we are consenting adults, and either respect
attributes with a leading underscore as private - or willfully chose to
*not* do that because of good reasons.

And the double-underscore is used against name-clashes, not for
enhanced "privacy".

>>, javaesque getter methods,
> 
> What do you mean by that?
> 
> What I associate with Java getter method is mainly the "get" prefix, for
> Java introspection.

You have an attribute id, whatfor do you need a method id? If at some point
this id becomes a computed value - you introduce a property

And that's what Peter meant with "javanesque" - the exact reason why in java
everything is wrapped in getters/setters is that the language lacks a
property-mechanism, so to present a consistent interface over several
iterations of the code, one has to introduce them for every single
attribute - regardless of their future destiny.

> 
>> unidiomatic None-checks
> 
> What's the idiomatic Python way for an optional thing?

None is a singleton, so the idiomatic check is for object identity:

  foo = None
  foo is None


Diez