如何访问在python中的函数内部声明的变量

Question

I have the following code that reads the configuration file and stores the results in some variables as a list

import ConfigParser

def read_config_file():
    config = ConfigParser.ConfigParser()
    cnf_path = 'config_files/php.sr'
    config.read(cnf_path)
    if config.has_section('basic'):
        if config.has_option('basic', 'basic'):
            php_bsc_mdls = config.get('basic', 'basic').split(',')
    if config.has_section('advance'):
        if config.has_option('advance','advance'):
            php_adv_mdls = config.get('advance', 'advance').split(',')

Now i want to get the result variables php_bsc_mdls and php_adv_mdls from the function something like read_config_file.php_bsc_mdls or read_config_file.php_adv_mdls

So is it possible to access/get the variables from the python function ?

Answer 1

You just need to return them. They cease to exist when the function ends.

def read_config_file():
    config = ConfigParser.ConfigParser()
    cnf_path = 'config_files/php.sr'
    config.read(cnf_path)
    if config.has_section('basic'):
        if config.has_option('basic', 'basic'):
            php_bsc_mdls = config.get('basic', 'basic').split(',')
    if config.has_section('advance'):
        if config.has_option('advance','advance'):
            php_adv_mdls = config.get('advance', 'advance').split(',')

    if php_bsc_mdls and php_adv_bls:
        return php_bsc_mdls,php_adv_mdls
    elif php_bsc_mdls:
        return php_bsc_mdls, None

Other approach would be a class where you save them to class variables. And later get those values from the class, not the function.

Or like this:

def read_config_file():
    php_bsc_mdls = None
    php_adv_mdls = None
    config = ConfigParser.ConfigParser()
    cnf_path = 'config_files/php.sr'
    config.read(cnf_path)
    if config.has_section('basic'):
        if config.has_option('basic', 'basic'):
            php_bsc_mdls = config.get('basic', 'basic').split(',')
    if config.has_section('advance'):
        if config.has_option('advance','advance'):
            php_adv_mdls = config.get('advance', 'advance').split(',')

    return php_bsc_mdls, php_adv_mdls

In either case, you need to check the return values where ever you call the function. If the values are none or not.

Answer 2

def read_config_file():
  php_bsc_mdls, php_adv_mdls = None, None # Init to None.
  ...
  return php_bsc_mdls, php_adv_mdls # Return at end.

# Get results
basic, advanced = read_config_file()

Alternatively, you could just make a class for this.

class Config:
  php_adv_mdls = None
  php_bsc_mdls = None
  @staticmethod
  def read_config_file():
    if not Config.php_adv_mdls and not Config.php_bsc_mdls:
      # Load the data here.
      config = ConfigParser.ConfigParser()
      ...
      Config.php_adv_mdls = config.get...
      Config.php_bsc_mdls = config.get...

Use the class variables and static methods to load your config files once .

Config.php_adv_mdls # None
Config.read_config_file() # Loads the data from config.
Config.read_config_file() # Will only attempt another load if either 
                          # class variable in not valid.
Config.php_bsc_mdls       # If successful, will be initialize with data.

Answer 3

As it was said it would be reasonable to do this with return.

But...

In python functions are objects, so you can do smth like this:

def a():
    a.x = 10

a()
print a.x    # >> 10

Last though not an example of good code, in this case.