Call property getter, setter, deleter - Python

Question

I'm getting the error "Type error: 'locationTile' is not a callable object when trying to call its fdel() method. Code:

class GamePlayLocationTiles(object):
    """The stuff needed for game play"""
    _locationTiles = []

    def locationTiles():
        doc = "property locationTiles's doc string"
        def fget(self):
            return self._locationTiles[0]
        def fset(self, value):
            self._locationTiles = value[0]
        def fdel(self):
            del self._locationTiles[0]
        return locals()  # credit: David Niergarth
    locationTiles = property(**locationTiles())

    def __init__(self):
        self.fill_location_tiles_list()

different module:

import game_play_model

class GamePlayController:
    """perform operations on the game_play_model"""

    def __init__(self):
        self.the_game_location_tiles = game_play_model.GamePlayLocationTiles()
        self.shuffle_location_tiles()


    def shuffle_location_tiles(self):
        self.the_game_location_tiles.locationTiles().fdel() //this line causes the error

def main():
    the_game_play_controller = GamePlayController()

if __name__ == '__main__':
    main()

Just trying to delete it as a test on accessing a private variable with a getter, setter, deleter.

Answer 1

def shuffle_location_tiles(self):
    del self.the_game_location_tiles.locationTiles

---

The fdel function should not be called directly. It will be called for you when the instance tries to delete the property.

For example,

class Foo(object):
    def x():
        def fget(self):
            """I'm the 'x' property."""
            return self._x

        def fset(self, value):
            self._x = value

        def fdel(self):
            print('deleting x')
            del self._x
        return locals()
    x = property(**x())

    def __init__(self):
        self._x = None


c = Foo()
del c.x
# deleting x

---

self.the_game_location_tiles.locationTiles() raises the error

"Type error: 'locationTile' is not a callable

because self.the_game_location_tiles.locationTiles calls fget and returns the value, self._locationTiles[0]. That value happens to not be callable.

You could access the property itself using GamePlayLocationTiles.locationTiles, and call fdel with

GamePlayLocationTiles.locationTiles.fdel(self.the_game_location_tiles)

but there is no reason to do that when you can just use the statement

del self.the_game_location_tiles.locationTiles

Answer 2

The point of using property is that you're not using the functions directly, but use common Python idioms to get/set/delete.

In this case, you would not be calling self.the_game_location_tiles.locationTiles().fdel(), but instead del self.the_game_location_tiles.locationTiles, which would call your fdel() method.

The same goes for getting and setting:

• self.the_game_location_tiles.locationTiles will use your fget.
• self.the_game_location_tiles.locationTiles = y will use your fset.

Answer 3

def locationTiles():
    doc = "property locationTiles's doc string"
    def fget(self):
        return self._locationTiles[0]
    def fset(self, value):
        self._locationTiles = value[0]
    def fdel(self):
        del self._locationTiles[0]
    return locals()  # credit: David Niergarth

locationTiles = property(**locationTiles()) # This redefines locationTiles to a variable

I see that you have a function and a variable both given the same name. This could cause problems with the execution. When you try to reference the function locationTiles(), Python sees it as the variable locationTiles

def shuffle_location_tiles(self):
    self.the_game_location_tiles.locationTiles().fdel() //this line causes the error