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Python Style Guide

Readability counts. One of Guido’s key insights is that code is read much more often than it is written.  The following suggestions of Python style is a summary of the ones in [PEP 8]

Blank lines

  • Separate top-level function and class definitions with two blank lines.
  • Method definitions inside a class are separated by a single blank line.
  • Extra blank lines may be used (sparingly) to separate groups of related functions.
  • Use blank lines in functions, sparingly, to indicate logical sections.

Avoid using spaces

Immediately inside parentheses, brackets or braces:

- YES: spam(ham[1], {eggs: 2})
- NO:  spam( ham[ 1 ], { eggs: 2 } )

Immediately before a comma, semicolon, or colon:

- YES: if x == 4: print x, y; x, y = y, x
- NO:  if x == 4 : print x , y ; x , y = y , x

More than one space around an assignment (or other) operator to align it with another.

- YES:
x = 1
y = 1
long_var = 3
- NO:
x             = 1
y             = 1
long_var = 3

Around the = sign when used to indicate a keyword argument or a default parameter value..

- YES:
def complex(real, imag=0.0):
    return magic(r=real, i=imag)
- NO:
def complex(real, imag = 0.0):
    return magic(r = real, i = imag)

Use spaces

Surround binary operators with a single space (, +, =, <, >, !, <>, <, >, in, not in, is, is not, etc.) If operators with different priorities are used, consider adding whitespace around the operators with the lowest priority(ies)

YES:
i = i + 1
submitted += 1
x = x*2 - 1
hypot2 = x*x + y*y
c = (a+b) * (a-b)
- NO:
i=i+1
submitted +=1
x = x * 2 - 1
hypot2 = x * x + y * y
c = (a + b) * (a - b)

Naming conventions

  • Package or module names:
    • module
    • module_name
    • Classes:
    • CamelCase (usually nouns)
  • Methods:
    • mixedCase (usually actions)
  • Constants:
    • UPPER_WITH_UNDERSCORE

Use library functions

Use libraries functions whenever is possible. Avoid using system commands.

- YES:
moveFile(sourceFile, destFile)
cleanPattern(“*.log”)
self._getExtraPath(“a”, “b”, “file.log”)
- NO:
runJob(“mv”, sourceFile + “ “ + destFile)
runJob(“rm”, “*.log”)
os.path.join(self.workingDir, “a/b/file.log”)