.value properties for widgets

How do you feel about creating .value getter and setter properties for the widgets?

e.g.

a value property would allow CheckBox value to be get and set as a boolean

class CheckBox(CheckButton):

    @property
    def value(self):
        return (self.get_value() == 1)

    @value.setter
    def value(self, value):
        if value:
            self.select()
        else:
            self.deselect()

check = CheckBox()
if check.value:
    check.value = False
    

The same value property could be created for all widgets allowing a simple interface to get and set its value.

[DavidWhaleMEF]

This is all about formally managing the deprecation process of your API methods in a controlled manner, and there are ways and means to do that.

The problem with saying ‘they can always use an older version of the API’ is that they are bound to want the shiny new features anyway even if on the old API, but probably won’t have the skills or time to do a massive merge to get those new features retro-fitted, or won’t have the time to update their existing homework to the new style.

You can use some getattr magic to delegate to the new inner tk, and make that delegation optional. getattr is only called if the class does not already have that method/attribute defined in it’s attribute dictionary.

In early releases, leave deprecated methods enabled by default. In later releases, disable deprecated by default. That way you can use both styles interchangeably, but the day that you flip the default ENABLE_DEPRECATED to False, the user can still set it to True at runtime if they want to use the old way. Here is a general design pattern for that.

It gives your users a way to migrate gradually, without breaking old code (or if you do break old code, users can easily flip the switch to fix it).

class MyClass():
    ENABLE_DEPRECATED = True

    def __getattr__(self, name):
        if ENABLE_DEPRECATED and hasattr(self.tk, name):
            print("warning: Using deprecated method:%s" % str(name))
            return getattr(self.tk, name)
        else:
            raise AttributeError("No such attribute:%s" % str(name))

c = MyClass()
c.old_method() # works
c.ENABLE_DEPRECATED = False
c.old_method() # get error

[lawsie]

Added these to 0.4 where they make sense, but maintained backwards compatibility.