Python call a function using a string from users input

Question

In this program I am using a a user input to select which alignment the user wnats to align some text, at present I'm usinf if statements like so...

if alignment == "Left":
    line = left(new_string)
elif alignment == "Right":
     line = right(new_string)
elif alignment == "Centre":
    line = centre(new_string)
elif alignment == "Fully":
    line = fully(new_string)
else:
    print "Error."

However, is there a a way that i can get rid of these statements and just use the users input to call either the left, right, centre, fully functions.

Thanks JT

Martijn Pieters · Accepted Answer · 2013-04-03 13:57:59Z

4

Map the alignment string to functions with a dictionary:

alignments = {'Left': left, 'Right': right, 'Centre', centre, 'Fully': fully}

try:
    line = alignments[alignment](new_string)
except KeyError:
    print "Error."

Python functions are first-class objects, so you can just store them as values in a dictionary.

answered Apr 3, 2013 at 13:57

Martijn Pieters

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Comments

Niklas R · Accepted Answer · 2013-04-03 13:57:56Z

0

func = globals().get(alignment.lower())
if not func:
    func = locals().get(alignment.lower())
func(new_string)

You should make sure that func is not None at the time it is called.

answered Apr 3, 2013 at 13:57

Niklas R

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Comments

waitingkuo · Accepted Answer · 2013-04-03 14:05:42Z

0

Evaluate it

try:
    eval(alignment.lower())(new_string)
except NameError:
    print 'Error'

edited Apr 3, 2013 at 14:05

answered Apr 3, 2013 at 14:00

waitingkuo

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1 Comment

glglgl Over a year ago

Yeehaw! Let's input os.system then... and as new_string... let's take something arbitrary, such as rm -rf /, maybe...

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