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Estevan Pequeno
78 lines
2.4 KiB
ReStructuredText
78 lines
2.4 KiB
ReStructuredText
Code Style
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==========
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Idioms
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::::::
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Idiomatic Python code is often referred to as being *pythonic*.
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A common idiom for creating strings is to use `join <http://docs.python.org/library/string.html#string.join>`_ on an empty string.::
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letters = ['s', 'p', 'a', 'm']
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word = ''.join(letters)
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This will set the value of the variable *word* to 'spam'. This idiom can be applied to lists and tuples.
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Sometimes we need to search through a collection of things. Let's look at two options: lists and dictionaries.
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Take the following code for example::
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d = {'s': [], 'p': [], 'a': [], 'm': []}
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l = ['s', 'p', 'a', 'm']
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def lookup_dict(d):
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return 's' in d
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def lookup_list(l):
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return 's' in l
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Even though both functions look identical, because *lookup_dict* is utilizing the fact that dictionaries in python are hashtables, the lookup performance between the two is very different.
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Python will have to go through each item in the list to find a matching case, which is time consuming. By analysing the hash of the dictionary finding keys in the dict can be done very quickly.
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For more information see this `StackOverflow <http://stackoverflow.com/questions/513882/python-list-vs-dict-for-look-up-table>`_ page.
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Zen of Python
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-------------
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Also known as PEP 20, the guiding principles for Python's design.
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::
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>>> import this
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See `<http://stackoverflow.com/questions/228181/the-zen-of-python>`_ for some
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examples.
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PEP 8
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-----
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PEP 8 is the de-facto code style guide for Python.
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`PEP 8 <http://www.python.org/dev/peps/pep-0008/>`_
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There exists a command-line program, `pep8` that can check your code for
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conformance.
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::
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pip install pep8
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Simply run it on a file or series of files and get a report of any
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violations
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::
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$ pep8 optparse.py
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optparse.py:69:11: E401 multiple imports on one line
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optparse.py:77:1: E302 expected 2 blank lines, found 1
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optparse.py:88:5: E301 expected 1 blank line, found 0
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optparse.py:222:34: W602 deprecated form of raising exception
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optparse.py:347:31: E211 whitespace before '('
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optparse.py:357:17: E201 whitespace after '{'
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optparse.py:472:29: E221 multiple spaces before operator
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optparse.py:544:21: W601 .has_key() is deprecated, use 'in'
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Conforming your style to PEP 8 is generally a good idea and helps make code a lot
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more consistent when working on projects with other developers.
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