处理大量常数的最有效方法

Question

I am writing a program that, depending on a certain values from an Excel table, makes an API call. There are 2 conditions from the table that will be checked:

• Language
• Provider

Depending on those two values a different set of constants is needed for the API call:

def run_workflow(provider, language, workflow):

    if provider == 'xxxx' and language == 0:

    wf_ready = provider_ready
    wf_unverified = provider_unverified
    wf_active = provider_active
    wf_another = provider_another
    wf_closed = provider_closed
    wf_wrongid = provider_wrongid

    elif provider == 'yyyy' and language == 0:

    wf_ready = provider_ready
    wf_unverified = provider_unverified
    wf_active = provider_active
    wf_another = provider_another
    wf_closed = provider_closed
    wf_wrongid = provider_wrongid

    elif ...


    if workflow == 'ready':
    response = requests.post(API + wf_ready),headers=header, data=json.dumps(conversation))

    elif workflow == 'unverified':
    response = requests.post(API + wf_unverified),headers=header, data=json.dumps(conversation))

    elif ...

There are 2 provider and 7 different languages and I am trying to figure out the most efficient (and Pythonic way) to handle this scenario and came up with creating a class for each language:

class Workflow_Language():

  def english(self):

    self.provider_unverified = 1112
    self.provider_ready = 1113
    self.provider_active = 1114
    self.provider_vip = 1115

  def russian(self):

    self.provider_unverified = 1116
    self.provider_ready = 1117
    self.provider_active = 1118
    self.provider_vip = 1119

  def ...

...

Is there maybe a better way to handle this?

Answer 1

One way is to map constants to appropriate handlers:

class LanguageData:
    def __init__(self, unverified, ready, active, vip):
        self.unverified = unverified
        self.ready = ready
        self.active = active
        self.vip = vip

def english():
    return LanguageData(1,2,3,4)

def russian():
    return LanguageData(5,6,7,8)

LANGUAGE_MAP = {'en': english, 'ru': russian}

I've made up 'en', 'ru' values for clarity. It seems that 0 is in your case? Also note that english and russian are standalone functions. Finally the LanguageData class is not mandatory, you can simply return a dictionary from those functions. But workin with attributes instead of string keys seems easier to maintain.

And then in the code:

def run_workflow(provider, language, workflow):
    lang_data = LANGUAGE_MAP[language]()
    if workflow == 'ready':
        url = API + data.ready
    elif workflow == 'unverified':
        url = API + data.unverified
    response = requests.post(url, headers=header, data=json.dumps(conversation))

Of course workflow can be wrapped in a similar way if there are more than 2 possible values.

Analogously for provider . Unless the action depends on both provider and language at the same time in which case you need a double map:

LANG_PROV_MAP = {
    ('en', 'xxxx'): first,
    ('ru', 'yyyy'): second,
}
def run_workflow(provider, language, workflow):
    data = LANG_PROV_MAP[(provider, language)]()
    ...

The original code can be simplified with a tricky decorator:

LANGUAGE_MAP = {}
def language_handler(lang):
    def wrapper(fn):
        LANGUAGE_MAP[lang] = fn
        return fn
    return wrapper

@language_handler('en')
def handler():
    return LanguageData(1,2,3,4)

@language_handler('ru')
def handler():
    return LanguageData(5,6,7,8)

Also note that if the data is "constant" (ie doesn't depend on the context) then you can completely omit callables to make everything even simplier:

LANGUAGE_MAP = {
    'en': LanguageData(1,2,3,4),
    'ru': LanguageData(5,6,7,8),
}
def run_workflow(provider, language, workflow):
    data = LANGUAGE_MAP[language]
    ...

Answer 2

The combination of the language and provider can compose the method name and the call will be invoked dynamically.

Example:

import sys

def provider1_lang2():
    pass

def provider2_lang4():
    pass

 # get the provider / lang and call the method dynamically
 provider = 'provider2'
 lang = 'lang4' 
 method_name = '{}_{}'.format(provider,lang)
 method =  getattr(sys.modules[__name__], method_name)
 method()