String to function with parameters

Question

I'm relatively new to Python, but I have a lot of experience in languages like C++ and Java. I am trying to parse a string to a function with parameters. This is what I got so far:

def DimLights(percent = 1.0):
 print 'Dimming lights to ' + "{:.2f}".format(percent * 100) + ' percent'
def TurnOffLights():
 print 'Turning off lights'
function_mappings = {'DimLights': DimLights,
 'TurnOffLights': TurnOffLights}
def select_function():
 while True:
 try:
 return function_mappings[raw_input('Please input the function you want to use')]
 except:
 print 'Invalid function, try again.'
while True:
 function = select_function()
 function()

It's working as long as I don't use any parameters, but I can't think of a solution that would work with parameters. Is there any way I can accomplish this?

• APerson: So you want to pass an argument into select_function() that would be in turn passed into the function you select?
• Brian Cain: unsolicited tip: please never leave an except: to catch all errors. You probably want KeyError and some select others here. But you probably don't want SyntaxError et al.
• TheKrane: @APerson: But what if I have more than one argument? Brian Cain: Thanks, I'll do that

Answer 1

Use str.split() with its maxsplit argument to strip off just the actual command, and argparse to parse the arguments.

• TheKrane: I'm sorry I'm a total noob when it comes to Python. Where exactly would I use str.split()?
• Ignacio Vazquez-Abrams: The input is a str, so you'd use it right on the input. inputline = raw_input(...); command, arguments = inputline.split(maxsplit=1)
• TheKrane: I don't know why I don't get this. So my input is for example: DimLights(1.0) Now I want to get rid of the'(1.0)' with inputline..split(maxsplit=1), right? And how do I parse the arguments. I feel really dumb right now.
• Ignacio Vazquez-Abrams: If you simplify the input to "DimLights 1.0" then you can use this. The parens are just noise unless you're either programming or doing math.
• TheKrane: Hmm I'm using python 2.7 and it gives me an error: split() takes no keyword arguments Is maxsplit a 3.4 feature?

Answer 2

Try this , Not a complete answer.But You can use it:

def DimLights(percent = 1.0):
 print 'Dimming lights to ' + "{:.2f}".format(percent * 100) + ' percent'
def TurnOffLights():
 print 'Turning off lights'
function_mappings = {'DimLights': DimLights,
 'TurnOffLights': TurnOffLights}
def select_function():
 while True:
 try:
 inp = raw_input('Please input the function you want to use:')
 inp = inp.split()
 return function_mappings[inp[0]], inp[1]
 except:
 print 'Invalid function, try again.'
 break
function, arg = select_function()
function(float(arg))
# while True:
# function = select_function
# function()
>>>Please input the function you want to use:DimLights 2.0
Dimming lights to 200.00 percent

Note

Put space between function and parameter. Also parameter is required.Otherwise Index error will occur

• TheKrane: Thank you so much! This helped a lot!