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I sometimes need to use multi-line strings, but in a nested block. This works, but the readability is really poor:

CONDITION1 = CONDITION2 = CONDITION3 = True if CONDITION1: if CONDITION2: s = """jkljkj dfkjslfds sqjdlqkj""" elif CONDITION3: s = """azeazea azeoiuaez azeytzae azetzae"""

Using:

if CONDITION1: if CONDITION2: s = """jkljkj dfkjslfds sqjdlqkj"""

(as suggested in Pythonic way to create a long multi-line string) is not an option because the string s would be:

jkljkj dfkjslfds sqjdlqkj

with unwanted left spaces.

Question: how to use multi-line strings in nested blocks with a good readability?

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2 Answers 2

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Wrap the string in a call to inspect.cleandoc and it will clean it up the same way docstrings get cleaned up (removing leading and trailing whitespace, and any level of common indentation).

>>> import inspect >>> s = """jkljkj ... dfkjslfds ... sqjdlqkj""" ... >>> print(s) jkljkj dfkjslfds sqjdlqkj >>> s = inspect.cleandoc(s) >>> print(s) jkljkj dfkjslfds sqjdlqkj

textwrap.dedent is also an option, but it's uglier, as it requires you to put no text on the first line, and explicitly use a line continuation character to ensure every line (not just the second and onwards) has identical leading indentation:

>>> print(textwrap.dedent('''\ ... The^backslash is a pain ... so I don't recommend this approach ... ''')) The^backslash is a pain so I don't recommend this approach

Note that while code blocks on SO don't show it properly, dedent left the empty final line (from putting the closing ''' on a line by itself), where cleandoc would have removed it.

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6 Comments

Thank you very much! For completeness, could you add the same example with dedent? (I can also edit myself if you're ok)
@Basj: Done. I think it's usually the inferior solution, so I didn't want to emphasize it, but it's occasionally useful.
Thanks! I accepted your answer. I think dedent might be useful when we actually want to keep a particular indentation but just remove the left spaces. Example: print(textwrap.dedent(""" some indented python code here """)).
@Basj: If it's just a single line, you'd just use .lstrip() for that (comments don't show newlines, so it's possible you intended to put newlines and I just can't see them).
textwrap.dedent can be useful if you want to preserve empty lines at the beginning or end of the block, as inspect.cleandoc works differently: "Empty lines at the beginning and end are subsequently removed." cleandoc vs. "Lines containing only whitespace are ignored in the input and normalized to a single newline character in the output." dedent
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Have you tried using '\'. For example:

if CONDITION1: if CONDITION2: s = "jkljkj "\ "dfkjslfds "\ "sqjdlqkj"
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Thank you, but not an option either, because my multiline string is very long. I don't want to have to manually add `" ... "` around each line.

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