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calling class/static method from class variable in python

Tags:

python

class

I'm trying to make a ImageLoader class handle the loading and processing of image resources like this:

class ImageLoader:
    TileTable = __loadTileTable('image path', some other variable)

    @staticmethod
    def _loadTileTable(arg1, arg2):
        blah blah

however, on compile i get: NameError: name '_loadTileTable' is not defined

If i replace the second line with TileTable = ImageLoader.__loadTileTable('image path', some other variable) then i get NameError: name 'ImageLoader' is not defined

As i'm going from C# to Python, static classes with static methods is what i'd use to implement this. However, i'm open to how I'd do this in general in python (that is, call static library functions that are only grouped together by their functionality).

UPDATE: After reading both answers, I'm getting a picture that what i'm trying to do probably isn't right. How would I go about imlementing ImageLoader so that I can do this:

Assuming that tile table returned an array

module1.py

aTile = ImageLoader.TileTable[1]

module2.py

anotherTile = ImageLoader.TileTable[2]

ideally, i'd populate TileTable just once.

Update:

Thanks for all the answers, I found my last answer to populating TileTable just once in the python modules doco

"A module can contain executable statements as well as function definitions. These statements are intended to initialize the module. They are executed only the first time the module is imported somewhere"

As for static class, i'm going to forgo classes and just make a module level variable.

like image 325
Joe Avatar asked Feb 15 '11 14:02

Joe


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1 Answers

Answering just the updated question, what you would do in Python is make TileTable a variable called tile_table in a module called imageloader. There is no reason at all to put any of this inside a class.

So then you get:

module1.py

import imageloader
aTile = imageloader.tile_table[1]

module2.py

import imageloader
anotherTile = imageloader.tile_table[2]

and imageload.py looks something like:

def _loadTileTable(arg1, arg2):
    pass # blah blah
tile_table = _loadTileTable('image path', other_var)

Think of a Python module as a singleton instance in other languages (which in fact it is) and you'll be able to reconcile this with any OO preconceptions you inherited from other languages.

like image 191
Duncan Avatar answered Oct 05 '22 14:10

Duncan