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Redefinition of unused python

Содержание
  1. Linters in Python — Part II
  2. Sample program:
  3. Conclusion:
  4. Share on

Linters in Python — Part II

We understood the difference between pep8 and linters in previous post. We’ll see various linters available in python with sample example.

Sample program:

I’ve written a error-prone program. It contains some unused imported modules, variables and arguments. It also overriddes one function. I’ve intentionally not followed pep8’s guidelines. Let’s see output of each linter.

#!/usr/bin/env python # encoding: utf-8 #unused modules import os import sys import argparse #unused global constant variable user_name = 'rootpy' def setUserName(self, name): fname = 'Prasad' u_name = name return u_name class User(object): def __init__(self, str, int): self.name = None self.password = None return def getUserPassword(self, password): self.password = password return def changeUserName(self, email): return print "How can I reach here?" def getUserPassword(self, password): return self.password == password

###PyChecker * It imports each module and compiles the each function, class and method for possible errors. * It determines the imported modules, classes and functions and creates a tree based on it. * It can’t process the module if there is an import error. * It compiles and executes the imported module so your code get executed. * For example: If you’ve SQL queries in python program then it executes every time which is bad (IMO) * Let’s pass the sample_program.py and analyze the output.

prasad@Rootpy: master ⚡ $ pychecker sample_program.py Processing module test_program_rootpy (test_program_rootpy.py). Warnings. sample_program.py:5: Imported module (os) not used sample_program.py:6: Imported module (sys) not used sample_program.py:7: Imported module (argparse) not used sample_program.py:15: self is argument in function sample_program.py:16: Local variable (fname) not used sample_program.py:23: Parameter (int) not used sample_program.py:23: Parameter (str) not used sample_program.py:32: Redefining attribute (getUserPassword) original line (28) FAIL: 1 prasad@Rootpy: master ⚡ $
  • It detects following errors:
    • unused imported module, local variable and arguments errors.
    • self is argument in function
    • unused global variable user_name.
    • pep8 related errors (some linters detect it).

    ###PyFlake * It is a static code analyzer as It identifies errors without executing python code. * It is faster than PyChecker because it doesn’t import any module and execute it. * Let’s see output for sample_program.py

    prasad@Rootpy: master ⚡ $ pyflakes sample_program.py sample_program.py:5: 'os' imported but unused sample_program.py:6: 'sys' imported but unused sample_program.py:7: 'argparse' imported but unused sample_program.py:16: local variable 'fname' is assigned to but never used sample_program.py:32: redefinition of unused 'getUserPassword' from line 28 FAIL: 1 prasad@Rootpy: master ⚡ $
    • It detects unused imported module, local variable and arguments related errors.
    • It doesn’t detect following errors:
      • Unused global variable user_name.
      • pep8 style guide related error.
      • Self is used as argument in function
      • Redefining parameters like int, str which are built-in data type in python

      ###Flake8 * It is a static code analyzer. Actually it is combination of pep8 and PyFlake. * It identifies programming errors as well as pep8 style-guide errors. * Let’s check what it gives on sample_program.py

      prasad@Rootpy: master ⚡ $ flake8 sample_program.py sample_program.py:5:1: F401 'os' imported but unused sample_program.py:6:1: F401 'sys' imported but unused sample_program.py:7:1: F401 'argparse' imported but unused sample_program.py:15:1: E303 too many blank lines (3) sample_program.py:16:5: F841 local variable 'fname' is assigned to but never used sample_program.py:32:5: F811 redefinition of unused 'getUserPassword' from line 28 sample_program.py:39:1: W391 blank line at end of file FAIL: 1 prasad@Rootpy: master ⚡ $
      • It detects following errors:
        • unused imported module, local variable, arguments error.
        • pep8 related errors like blank line, too many blank line etc.
        • unused global variable user_name.
        • Self is used as argument in function
        • Parameters like int, str which are built-in data type in python

        ###PyLint * It is a static code analyzer which checks errors in python code. * It looks for bad codes and tries to enforce a coding standard. * It displays statistics about the number of warnings and errors found in different files. * It also gives overall mark, based on numbers of warnings and errors. Some key features as below: * Refactoring: * It also detects duplicates codes. * Fully Customizable: * You can create your own .pylintrc and modify which errors are important for you. * UML Diagram: * It creates UML diagrams for python code using Pyreverse * Editor and IDE integration: * Editor Integration are available for various editors like emacs, vim and eclipse * IDE integration are also available for various IDEs like spyder, editra and TextMate * Check list of supported editors and IDEs * It gives very descriptive output. The output is divided into two categories message and reports. * message contains warnings, errors, coding standard convention, Refactoring and Fatal errors. * error messages type: * [R]efactor for a “good practice” metric violation * [C]onvention for coding standard violation * [W]arning for stylistic problems, or minor programming issues * [E]rror for important programming issues (i.e. most probably bug) * [F]atal for errors which prevented further processing. * Reports contains statistics information for by type, raw metrics, duplication, message by category etc. * Let’s run pylint on sample_program.py and check the output.

        prasad@Rootpy: master ⚡ $ pylint sample_program.py ************* Module sample_program C: 1, 0: Missing module docstring (missing-docstring) C: 11, 0: Invalid constant name "user_name" (invalid-name) C: 15, 0: Invalid function name "setUserName" (invalid-name) C: 15, 0: Missing function docstring (missing-docstring) W: 15,16: Unused argument 'self' (unused-argument) W: 16, 4: Unused variable 'fname' (unused-variable) C: 21, 0: Missing class docstring (missing-docstring) W: 23,28: Redefining built-in 'int' (redefined-builtin) W: 23,23: Redefining built-in 'str' (redefined-builtin) W: 23,28: Unused argument 'int' (unused-argument) W: 23,23: Unused argument 'str' (unused-argument) C: 28, 4: Invalid method name "getUserPassword" (invalid-name) C: 28, 4: Missing method docstring (missing-docstring) E: 32, 4: method already defined line 28 (function-redefined) C: 32, 4: Invalid method name "getUserPassword" (invalid-name) C: 32, 4: Missing method docstring (missing-docstring) C: 35, 4: Invalid method name "changeUserName" (invalid-name) C: 35, 4: Missing method docstring (missing-docstring) W: 37, 8: Unreachable code (unreachable) W: 35,29: Unused argument 'email' (unused-argument) R: 35, 4: Method could be a function (no-self-use) W: 5, 0: Unused import os (unused-import) W: 6, 0: Unused import sys (unused-import) W: 7, 0: Unused import argparse (unused-import) Report ====== 22 statements analysed. Statistics by type ------------------ +---------+-------+-----------+-----------+------------+---------+ |type |number |old number |difference |%documented |%badname | +=========+=======+===========+===========+============+=========+ |module |1 |NC |NC |0.00 |0.00 | +---------+-------+-----------+-----------+------------+---------+ |class |1 |NC |NC |0.00 |0.00 | +---------+-------+-----------+-----------+------------+---------+ |method |4 |NC |NC |25.00 |75.00 | +---------+-------+-----------+-----------+------------+---------+ |function |1 |NC |NC |0.00 |100.00 | +---------+-------+-----------+-----------+------------+---------+ Raw metrics ----------- +----------+-------+------+---------+-----------+ |type |number |% |previous |difference | +==========+=======+======+=========+===========+ |code |19 |55.88 |NC |NC | +----------+-------+------+---------+-----------+ |docstring |1 |2.94 |NC |NC | +----------+-------+------+---------+-----------+ |comment |4 |11.76 |NC |NC | +----------+-------+------+---------+-----------+ |empty |10 |29.41 |NC |NC | +----------+-------+------+---------+-----------+ Duplication ----------- +-------------------------+------+---------+-----------+ | |now |previous |difference | +=========================+======+=========+===========+ |nb duplicated lines |0 |NC |NC | +-------------------------+------+---------+-----------+ |percent duplicated lines |0.000 |NC |NC | +-------------------------+------+---------+-----------+ Messages by category -------------------- +-----------+-------+---------+-----------+ |type |number |previous |difference | +===========+=======+=========+===========+ |convention |11 |NC |NC | +-----------+-------+---------+-----------+ |refactor |1 |NC |NC | +-----------+-------+---------+-----------+ |warning |11 |NC |NC | +-----------+-------+---------+-----------+ |error |1 |NC |NC | +-----------+-------+---------+-----------+ Messages -------- +-------------------+------------+ |message id |occurrences | +===================+============+ |missing-docstring |6 | +-------------------+------------+ |invalid-name |5 | +-------------------+------------+ |unused-argument |4 | +-------------------+------------+ |unused-import |3 | +-------------------+------------+ |redefined-builtin |2 | +-------------------+------------+ |unused-variable |1 | +-------------------+------------+ |unreachable |1 | +-------------------+------------+ |no-self-use |1 | +-------------------+------------+ |function-redefined |1 | +-------------------+------------+ Global evaluation ----------------- Your code has been rated at -2.73/10 FAIL: 30 prasad@Rootpy: master ⚡ $
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