CODEWITHSUNDEEP
pythonpython-2.7
Dumi B
Dumi B

Reputation: 151

Using raw_input() as a parameter

def func(raw_input()):
    #stuff goes here..

Why can't you use raw_input() as a parameter?

Upvotes: 0

Views: 302

Answers (3)

Conic
Conic

Reputation: 1198

Try this strange OOP solution. 

class Runnable:
    def __init__(self,function,  *args, **kwargs):
        self.function = function
        self.args = args
        self.kwargs = kwargs
    def run(self):
        return self.function(*self.args, **self.kwargs)

Runnable Loads up an object with a function and arguments. .run() executes when you're ready.

Here is its usage: 

def func(runnable_thing):
    print(runnable_thing.run())   

super_raw = Runnable(raw_input, "Please Type your Input: ")

func(super_raw) # prints input from raw

The cool thing is that the Runnable class I made works on other functions with larger params as well. 

import datetime
foo = Runnable(datetime.datetime, 2016, 12, 15 ) ## foo is not yet a datetime object 
bar = foo.run() ## bar is a datetime object

If you're not a fan of the .run() at the end of it, then we can follow Deloith's suggestion to use __call__() to make Runnable feel like a function. 

class Runnable:
    def __init__(self,function,  *args, **kwargs):
        self.function = function
        self.args = args
        self.kwargs = kwargs
    def __call__(self):
        return self.function(*self.args, **self.kwargs)

From this point on, it really feels like we've created a new function. 

   def func(runnable_thing):
        print(runnable_thing()) 

    super_raw = Runnable(raw_input, "Please Type your Input: ")  

    func(super_raw) # prints input from raw

Try that on for size, and let me know how you like it.

Upvotes: 0

Jean-François Fabre
Jean-François Fabre

Reputation: 140148

You can't.

BTW, You could falsely think that using named parameters could work:

def func(s=raw_input()):
    print(s)

func()
func()

then only problem is that it just seems to work. First time calling func(), s is evaluated by prompting you to enter a string.

Second time, default value for s is known and you're not prompted.

Upvotes: 2

Prune
Prune

Reputation: 77827

Because the return value of a function call is semantically distinct from a parameter. raw_input() returns a string; a parameter must be an identifier that takes on the value passed in.

Upvotes: 3

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