Correct way to put long function calls on multiple lines

问题

I have a long function, as seen below:

hash_correct = hashlib.md5(salt + password)).digest().encode("base64")

I'd like to split it up into two lines but am not sure of the correct way to do this in Python?

Thanks.

回答1:

The coding guidelines limiting length of lines is there, in part, to make the code more readable. In your case of chained method calls, the meaning is not clear. You should pick some temporary variable names for the intermediate values so that a reader of the code can understand the chain easily.

One example might be:

safe_md5 = hashlib.md5(salt + password)
crypto_hash = safe_md5.digest()
hash_correct = crypto_hash.encode('base64')

This leads the reader down a garden path to understanding. Very little is lost in performance, and the additional code is all added for purpose.

回答2:

Prefer Charles Merram's answer, but I thought this worth noting as working but ugly and to be discouraged. Because '.' is a lexical delimiter, the following worked:

>>> 'abc def' . split()
['abc', 'def']
>>> 'abc def' . \
... split()
['abc', 'def']
>>> sys.version
'2.6.4 (r264:75706, Dec  7 2009, 18:45:15) \n[GCC 4.4.1]'

but don't do that.

来源：https://stackoverflow.com/questions/2550439/correct-way-to-put-long-function-calls-on-multiple-lines