Python PEP8 encoding specification expressions and spaces in statements

Can't stand the Things

Avoid using extraneous spaces in the following situations:

• Immediately after the parentheses, brackets, or curly braces.

Yes:spam (Ham[1], {eggs:2}) No:  spam (ham[1], {eggs:2})

• Close to the comma, semicolon, or colon.

Yes:if x = = 4:print x, y; X, y = y, xno:  if x = = 4:print x, y; x, y = y, X

• However, a colon is like a two-dollar operator in a slice and should have the same number of spaces on both sides (consider it the lowest-priority operator). In an extended slice operation, all colons must have the same spacing. Exception: When a slice parameter is omitted, the space is omitted.
  Recommended:

Ham[1:9], Ham[1:9:3], Ham[:9:3], Ham[1::3], Ham[1:9:]ham[lower:upper], Ham[lower:upper:], ham[lower::step]ham[lower+ offset:upper+offset]ham[: Upper_fn (x): Step_fn (x)], ham[:: Step_fn (x)]ham[lower + offset:upper + offset]

Not recommended

Ham[lower + Offset:upper + offset]ham[1:9], Ham[1:9], Ham[1:9: 3]ham[lower:: upper]ham[: Upper]

• Close to the opening parenthesis of the function argument.

Yes:spam (1) No:  spam (1)

• Close to the left parenthesis of the index or slice.

yes:dct[' key ' = lst[index]no:  DCT [' key '] = LST [index]

• To align with another assignment statement, add more spaces to the assignment operator attachment.
  Recommended:

x = 1y = 2long_variable = 3

Not recommended:

X             = 1y             = 2long_variable = 3

Other recommendations

• Avoid adding spaces at the tail. Because trailing spaces are usually invisible, there is confusion: for example, a newline character followed by a backslash is not counted as a continuation of the line. Some editors do not preserve trailing spaces, and many items (like CPython) filter out trailing spaces in Pre-commit hook calls.

• Always add a space on both sides of the two-dollar operator: Assignment (=), increment assignment (+=,-=), Comparison (==,<,>,!=,<>,<=,>=,in,not,in,is,is not), Boolean (and, or, not).

• If you use operators with different precedence, consider adding spaces around the operators with the lowest precedence. Sometimes you need to judge by yourself; however, do not use more than one space, and use the same number of spaces on both sides of the two-dollar operator.
  Recommended:

i = i + 1submitted + = 1x = X*2-1hypot2 = x*x + Y*yc = (a+b) * (A-B)

Not recommended:

i=i+1submitted +=1x = x * 2-1hypot2 = x * x + y * yc = (A + b) * (a)

• Do not add a space near = when you are setting a keyword parameter or a default parameter value.
  Recommended:

def complex (Real, imag=0.0):    return Magic (R=real, I=imag)

Not recommended:

def complex (real, imag = 0.0):    return Magic (r = Real, I = imag)

• Functional annotations should use the general rules of the colon, and add spaces on both sides when used. (Refer to the function note below to get more information)
  Recommended:

def munge (input:anystr): ... def munge ()-Anystr: ...

Not recommended:

def munge (input:anystr): ... def munge ()->posint: ...

• When assigning a value to a parameter with a type comment, add a space on both sides (only for those parameters that have type notes and default values).
  Recommended:

def munge (sep:anystr = none): ... def munge (input:anystr, sep:anystr = None, limit=1000): ...

Not recommended:

def munge (Input:anystr=none): ... def munge (input:anystr, limit = 1000): ...

• Compound statements (multiple statements in the same row) are generally not allowed.
  Recommended:

if foo = = ' blah ':    do_blah_thing () Do_one () Do_two () Do_three ()

Not recommended:

if foo = = ' blah ': do_blah_thing () Do_one (); Do_two (); Do_three ()

• Although it is not a problem to put small blocks of code and if/for/while on the same line sometimes, it is not a good thing to do this with multiple lines of statements, but also to avoid long lines of code!
  Better not do this:

if foo = = ' blah ': do_blah_thing () for x in Lst:total + = Xwhile T < 10:t = delay ()

Not recommended:

if foo = = ' blah ': do_blah_thing () else:do_non_blah_thing () try:something () Finally:cleanup () Do_one (); Do_two (); Do_three (long, argument,                             list, like, this) if foo = = ' blah ': one (); both (); three ()

Python PEP8 encoding specification expressions and spaces in statements