Python defining function under condition

Question

Is this code correct in python?

def foo(flag):
    if flag:
        def bar():
           # Somthing
    else:
        def bar():
           # Somthing else
    bar()

foo(True)
foo(False)

if not what is a recommended way to set behavior of some function (bar) under? condition?

OK The real code is following

# Building replaceFunc based of ignore_case and use_regexp flags
if not ignore_case:
   if not use_regexp:
      def replaceFunc(string, search, replace):
          return string.replace(search, replace)
   else:
      def replaceFunc(string, search, replace):
          pattern = re.compile(search)
          return pattern.sub(replace, string)
else:
   if not use_regexp:
       # There is no standard puthon function for replacing string by ignoring case
       def replaceFunc(string, search, replace):
          # implementation from http://stackoverflow.com/questions/919056/case-insensitive-replace
           return string
   else:
        def replaceFunc(string, search, replace):
            pattern = re.compile(search, re.IGNORECASE)
            return pattern.sub(replace, string

Why don't you put the if inside bar? Why do you need bar at all? — BlackBear, Feb 19 '17 at 11:59
The real case is too complicated. I have tried to put simplified code. In real example bar is called inside for cycle. It also need to be passed to other function — ArmanHunanyan, Feb 19 '17 at 12:01
Such a reductive example does not allow anyone to give you a useful answer. Please [edit] to provide context. — jonrsharpe, Feb 19 '17 at 12:05
This is perfectly correct. Whether it is the best solution depends on many things, including personal preference. Anyway, it does seem like there could be better solutions... — zvone, Feb 19 '17 at 12:06

score 1 · Accepted Answer · answered Feb 19 '17 at 12:13

1

Here's one reasonable way to achieve what you want:

def bar1():
    return 'b1'

def bar2():
    return 'b2'

def foo(flag):
    bar = bar2 if flag else bar1
    return bar()

print(foo(False))
print(foo(True))

One benefit of defining the functions bar1() and bar2() outside of foo() is that they can be unit tested.

answered Feb 19 '17 at 12:13

FMc

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OK Thanks. This will work. Is the way to avoid from unneccary indiced names. In my case they will be bar1 bar2 bar3 bar4. Doesn't looks nice. – ArmanHunanyan Feb 19 '17 at 12:21
@ArmanHunanyan Sure, you can name the functions any way you like. Give them meaningful names — not `bar1`, `bar2`, etc. – FMc Feb 19 '17 at 12:47

Python defining function under condition

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