Using a string in if statement

Question

Can anyone explain what check is being performed on word in the statement if word: in the following code?

def simplify(text, space=" \t\n\r\f", delete=""):
    result = []
    word = ""
    for char in text:
        if char in delete:
            continue
        elif char in space:
            if word:
                result.append(word)
                word = ""
        else:
            word += char
    if word:
        result.append(word)
    return " ".join(result)

Is that =+ some cool new Python 3 thing or will that result in a TypeError? — matt
– matt, Commented May 1, 2014 at 17:55

ZekeDroid · Accepted Answer · 2014-05-01 17:48:36Z

7

A non empty string in python is always True, otherwise False. So if word is still your empty string it will be False, otherwise True.

answered May 1, 2014 at 17:48

ZekeDroid

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1 Comment

Eryk Sun Over a year ago

You can generalize this in terms of the special methods __bool__ and __len__. It falls back on str.__len__, since str doesn't define __bool__.

Santa · Accepted Answer · 2014-05-01 17:52:46Z

1

Why not try it for yourself in Python's REPL (that's one of the beauty of the language and languages in its class):

Python 2.7.6 (default, Mar 22 2014, 22:59:56) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> word = ""
>>> if word: print "I'm here"
... 
>>> word = "not empty"
>>> if word: print "I'm here"
... 
I'm here

answered May 1, 2014 at 17:52

Santa

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1 Comment

matt Over a year ago

This seems a bit contrived. If he knew what to test (empty vs non-empty string) he'd probably not be asking the question. :)

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