CODEWITHSUNDEEP
pythonpython-3.xdictionarymethods
stack_lech
stack_lech

Reputation: 1080

Python: methods are called when used as dict values while creation of the dict

I want to have a dispatcher dict{str: method} with methods in it. I want to iterate over the dispatcher keys and call the value as method, but when I run the Python script the methods get executed as soon as the dict is created:

from python.helper.my_client import Client

def deco_download(f):
    def f_download(*args, **kwargs):
        # some retry functionality here
        return json_data
    return f_download 

class Downloader:
    def __init__(self):
        self.attribute = 'some_value'

    @deco_download
    def download_persons(self, client, *args, **kwargs):
        return client.get_persons(*args, **kwargs)

    @deco_download
    def download_organizations(self, client, *args, **kwargs):
        return client.get_organizations(*args, **kwargs)

def run(self):
    dispatcher = {
        'person': self.download_persons(client),
        'organization': self.download_organizations(client)
    }

    for key in dispatcher:
        print("Downlading data for: {0}".format(key)
        dispatcher[key]

Unfortunately the methods are executed directly when the dispatcher dict is initialized before I call them in the for loop. I expect them to be called in the for loop and not during the construction of the dict however. What am I doing wrong here? Is it because of the decorator I am using?

Upvotes: 1

Views: 76

Answers (2)

Mike Scotty
Mike Scotty

Reputation: 10782

Simply don't execute the function during the creation of the dict:

def run(self):
    dispatcher = {
        'person': self.download_persons,
        'organization': self.download_organizations
    }

    for key in dispatcher:
        print("Downlading data for: {0}".format(key)
        dispatcher[key](client) # execute the function here

Upvotes: 1

Daniel Roseman
Daniel Roseman

Reputation: 600041

They're called because you call them. Don't do that; put the callables in the dict.

def run(self):
    dispatcher = {
        'person': self.download_persons,
        'organization': self.download_organizations
    }

    for key in dispatcher:
        print("Downlading data for: {0}".format(key)
        dispatcher[key](client)

Upvotes: 4

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