Question

I noticed I often write the following:

class X:
  def __init__(self, var1, var2, var3):
    self.var1 = var1
    self.var2 = var2
    self.var3 = var3
    # more code here

Is it a good idea to make a template that I can reuse instead of doing this every time? If so, how should I do that?

Answer 1

I wouldn’t suggest using such templates in production code, because

Explicit is better than implicit.

For throw-away prototypes it might be acceptable. Here is an example from the python recipes:

• http://code.activestate.com/recipes/577382-keyword-argument-injection-with-python-decorators/

It defines a decorator with can be attached to __init__:

def injectArguments(inFunction):
    """
    This function allows to reduce code for initialization 
    of parameters of a method through the @-notation
    You need to call this function before the method in this way: 
    @injectArguments
    """
    def outFunction(*args, **kwargs):
        _self = args[0]
        _self.__dict__.update(kwargs)
        # Get all of argument's names of the inFunction
        _total_names = \
            inFunction.func_code.co_varnames[1:inFunction.func_code.co_argcount]
        # Get all of the values
        _values = args[1:]
        # Get only the names that don't belong to kwargs
        _names = [n for n in _total_names if not kwargs.has_key(n)]

        # Match names with values and update __dict__
        d={}
        for n, v in zip(_names,_values):
            d[n] = v
        _self.__dict__.update(d)
        inFunction(*args,**kwargs)

    return outFunction

A test:

class Test:
    @injectArguments
    def __init__(self, name, surname):
        pass

if __name__=='__main__':
    t = Test('mickey', surname='mouse')
    print t.name, t.surname