Import instance of class from a different module
python
Solution
Trying to answer this question, if I understand you correctly: how do I keep a global atlas for all my species, an example of the Singleton pattern? See this SO question.
One way of doing this, simply, and Pythonically, is to have module in a file `directory.py` that contains all the directory-related code and a global `atlas` variable:
atlas = []
def add_to_world(obj, space=[0,0]):
species = {'obj' : obj.object_species,
'name' : obj.name,
'zone' : obj.zone,
'space' : space}
atlas.append( species )
def remove_from_world(obj):
global atlas
atlas = [ species for species in atlas
if species['name'] != obj.name ]
# Add here functions to manipulate the world in the directory
Then in your main script the different species could reference that global `atlas` by importing the `directory` module, thus:
import directory
class Species(object):
def __init__(self, object_species, name, zone = 'forest'):
self.object_species = object_species
self.name = name
self.zone = zone
directory.add_to_world(self)
class Llama(Species):
def __init__(self, name):
super(Llama, self).__init__('Llama', name)
class Horse(Species):
def __init__(self, name):
super(Horse, self).__init__('Horse', name, zone = 'stable')
if __name__ == '__main__':
a1 = Llama(name='LL1')
print directory.atlas
# [{'obj': 'Llama', 'name': 'LL1', 'zone': 'forest', 'space': [0, 0]}]
a2 = Horse(name='H2')
print directory.atlas
# [{'obj': 'Llama', 'name': 'LL1', 'zone': 'forest', 'space': [0, 0]},
# {'obj': 'Horse', 'name': 'H2', 'zone': 'stable', 'space': [0, 0]}]
directory.remove_from_world(a1)
print directory.atlas
# [{'obj': 'Horse', 'name': 'H2', 'zone': 'stable', 'space': [0, 0]}]
The code can be much improved, but the general principles should be clear.
Problem
I have a module named directory and another module named species. There will always only be one directory no matter how many species i have. In the directory module i have 1 directory class. Inside the Species module i have many different species classes. ``` #module named directory class directory: def __init__(self): ... def add_to_world(self, obj, name, zone = 'forrest', space = [0, 0]): ... #module named species class Species (object): def __init__(self, atlas): self.atlas = atlas def new(self, object_species, name, zone = 'holding'): self.object_species = object_species self.name = name self.zone = zone self.atlas.add_to_world(object_species, name) class Lama(Species): def __init__(self, name, atlas, zone = 'forrest'): self.new('Lama', name) self.at = getattr(Entity, ) self.atlas = atlas ``` The problem is that in each of my classes i have to pass the atlas object to that species. How can i just tell the species to get an instance from a different module. Example if i have an instance of 'atlas' in module named Entity with a class Entity, how can i tell all species with a few lines of code to grab that instance from Entity?