Is it possible to break a long line to multiple lines in Python?
PythonLine BreaksPython Problem Overview
Just like C, you can break a long line into multiple short lines. But in Python, if I do this, there will be an indent error... Is it possible?
Python Solutions
Solution 1 - Python
From PEP 8 - Style Guide for Python Code:
> The preferred way of wrapping long lines is by using Python's implied line > continuation inside parentheses, brackets and braces. If necessary, you > can add an extra pair of parentheses around an expression, but sometimes > using a backslash looks better. Make sure to indent the continued line > appropriately.
Example of implicit line continuation:
a = some_function(
'1' + '2' + '3' - '4')
On the topic of line breaks around a binary operator, it goes on to say:
> For decades the recommended style was to break after binary operators. > But this can hurt readability in two ways: the operators tend to get scattered across different columns on the screen, and each operator is moved away from its operand and onto the previous line.
> In Python code, it is permissible to break before or after a binary operator, as long as the convention is consistent locally. For new code Knuth's style (line breaks before the operator) is suggested.
Example of explicit line continuation:
a = '1' \
+ '2' \
+ '3' \
- '4'
Solution 2 - Python
There is more than one way to do it.
1). A long statement:
>>> def print_something():
print 'This is a really long line,', \
'but we can make it across multiple lines.'
2). Using parenthesis:
>>> def print_something():
print ('Wow, this also works?',
'I never knew!')
3). Using \ again:
>>> x = 10
>>> if x == 10 or x > 0 or \
x < 100:
print 'True'
Quoting PEP8:
> The preferred way of wrapping long > lines is by using Python's implied > line continuation inside parentheses, brackets and braces. If necessary, > you can add an extra pair of parentheses around an expression, but > sometimes using a backslash looks better. Make sure to indent the continued line > appropriately. The preferred place to break around a binary > operator is after the operator, not before it.
Solution 3 - Python
If you want to assign a long string to variable, you can do it as below:
net_weights_pathname = (
'/home/acgtyrant/BigDatas/'
'model_configs/lenet_iter_10000.caffemodel')
Do not add any comma, or you will get a tuple which contains many strings!
Solution 4 - Python
It works in Python too:
>>> 1+\
2+\
3
6
>>> (1+
2+
3)
6
Solution 5 - Python
When trying to enter continuous text (say, a query) do not put commas at the end of the line or you will get a list of strings instead of one long string:
queryText= "SELECT * FROM TABLE1 AS T1"\
"JOIN TABLE2 AS T2 ON T1.SOMETHING = T2.SOMETHING"\
"JOIN TABLE3 AS T3 ON T3.SOMETHING = T2.SOMETHING"\
"WHERE SOMETHING BETWEEN <WHATEVER> AND <WHATEVER ELSE>"\
"ORDER BY WHATEVERS DESC"
kinda like that.
There is a comment like this from acgtyrant, sorry, didn't see that. :/
Solution 6 - Python
DB related code looks easier on the eyes in multiple lines, enclosed by a pair of triple quotes:
SQL = """SELECT
id,
fld_1,
fld_2,
fld_3,
......
FROM some_tbl"""
than the following one giant long line:
SQL = "SELECT id, fld_1, fld_2, fld_3, .................................... FROM some_tbl"
Solution 7 - Python
As far as I know, it can be done. Python has implicit line continuation (inside parentheses, brackets, and strings) for triple-quoted strings ("""like this""") and the indentation of continuation lines is not important. For more information, you may want to read this article on lexical analysis, from python.org.