Python – What’s the best way to return multiple values from a function

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I have a function where I need to do something to a string. I need the function to return a boolean indicating whether or not the operation succeeded, and I also need to return the modified string.

In C#, I would use an out parameter for the string, but there is no equivalent in Python. I'm still very new to Python and the only thing I can think of is to return a tuple with the boolean and modified string.

Best Answer

def f(in_str):
    out_str = in_str.upper()
    return True, out_str # Creates tuple automatically

succeeded, b = f("a") # Automatic tuple unpacking

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Python – Calling a function of a module by using its name (a string)

Assuming module foo with method bar:

import foo
method_to_call = getattr(foo, 'bar')
result = method_to_call()

You could shorten lines 2 and 3 to:

result = getattr(foo, 'bar')()

if that makes more sense for your use case.

You can use getattr in this fashion on class instance bound methods, module-level methods, class methods... the list goes on.

Python – What’s the canonical way to check for type in Python

To check if o is an instance of str or any subclass of str, use isinstance (this would be the "canonical" way):

if isinstance(o, str):

To check if the type of o is exactly str (exclude subclasses):

if type(o) is str:

The following also works, and can be useful in some cases:

if issubclass(type(o), str):

See Built-in Functions in the Python Library Reference for relevant information.

One more note: in this case, if you're using Python 2, you may actually want to use:

if isinstance(o, basestring):

because this will also catch Unicode strings (unicode is not a subclass of str; both str and unicode are subclasses of basestring). Note that basestring no longer exists in Python 3, where there's a strict separation of strings (str) and binary data (bytes).

Alternatively, isinstance accepts a tuple of classes. This will return True if o is an instance of any subclass of any of (str, unicode):

if isinstance(o, (str, unicode)):

Best Answer

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Python – Calling a function of a module by using its name (a string)

Python – What’s the canonical way to check for type in Python

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