PyLint features

1. Master

1.1. Description

lint Python modules using external checkers.

This is the main checker controling the other ones and the reports generation. It is itself both a raw checker and an astng checker in order to: * handle message activation / deactivation at the module level * handle some basic but necessary stats'data (number of classes, methods...)

This checker also defines the following reports: * R0001: Total errors / warnings * R0002: % errors / warnings by module * R0003: Messages * R0004: Global evaluation

1.2. Messages

I0001:

Used to inform that a built-in module has not been checked using the raw checkers. This message belongs to the master checker.

I0010:

Used when an inline option is either badly formatted or can't be used inside modules. This message belongs to the master checker.

I0011:

Used when an inline option disable a message or a messages category. This message belongs to the master checker.

I0012:

Used when an inline option enable a message or a messages category. This message belongs to the master checker.

E0001:

Used when a syntax error is raised for a module. This message belongs to the master checker.

E0011:

Used when an unknown inline option is encountered. This message belongs to the master checker.

E0012:

Used when an bad value for an inline option is encountered. This message belongs to the master checker.

F0001:

Used when an error occured preventing the analyzing of a module (unable to find it for instance). This message belongs to the master checker.

F0002:

Used when an unexpected error occured while building the ASTNG representation. This is usually accomopagned by a traceback. Please report such errors ! This message belongs to the master checker.

F0003:

Used to indicate that the user asked to analyze a builtin module which has been skipped. This message belongs to the master checker.

2. Variables

2.1. Description

checks for * unused variables / imports * undefined variables * redefinition of variable from builtins or from an outer scope * use of variable before assigment

2.2. Messages

W0601:

Used when a variable is defined through the "global" statement but the variable is not defined in the static global scope. This message belongs to the variables checker.

W0611:

Used when an imported module or variable is not used. This message belongs to the variables checker.

W0612:

Used when a variable is defined but not used. This message belongs to the variables checker.

W0613:

Used when a function or method argument is not used. This message belongs to the variables checker.

W0621:

Used when a variable's name hide a name defined in the outer scope. This message belongs to the variables checker.

W0622:

Used when a variable or function override a built-in. This message belongs to the variables checker.

E0601:

Used when a local variable is accessed before it's assigment. This message belongs to the variables checker.

E0602:

Used when an undefined variable is accessed. This message belongs to the variables checker.

3. Basic

3.1. Description

checks for : * doc strings * modules / classes / functions / methods / arguments / variables name * number of arguments, local variables, branchs, returns and statements in functions, methods * required module attributes * dangerous default values as arguments * redefinition of function / method / class * uses of the global statement

This checker also defines the following reports: * R0101: Statistics by type

3.2. Messages

C0101:

Used when a variable has a too short name. This message belongs to the basic checker.

C0102:

Used when the name is listed in the black list (unauthorized names). This message belongs to the basic checker.

C0103:

Used when the name doesn't match the regular expression associated to its type (constant, variable, class...). This message belongs to the basic checker.

W0101:

Used when there is some code behind a "return" or "raise" statement, which will never be accessed. This message belongs to the basic checker.

W0102:

Used when a mutable value as list or dictionary is detected in a default value for an argument. This message belongs to the basic checker.

W0103:

Used when an attribute required for modules is missing. This message belongs to the basic checker.

W0121:

Used when you use the "global" statement, to discourage its usage. That doesn't mean you can not use it ! This message belongs to the basic checker.

W0122:

Used when you use the "exec" statement, to discourage its usage. That doesn't mean you can not use it ! This message belongs to the basic checker.

W0131:

Used when a module, function, class or method has no docstring. Some special methods like __init__ doesn't necessary require a docstring. This message belongs to the basic checker.

W0132:

Used when a module, function, class or method has an empty docstring (it would be to easy ;). This message belongs to the basic checker.

W0141:

Used when a black listed builtin function is used (see the bad-function option). Usual black listed functions are the ones like map, or filter , where Python offers now some cleaner alternative like list comprehension. This message belongs to the basic checker.

W0142:

Used when a function or method is called using *args or **kwargs to dispatch arguments. This doesn't improve readility and should be used with care. This message belongs to the basic checker.

E0101:

Used when the special class method __ini__ has an explicit return value. This message belongs to the basic checker.

E0102:

Used when a function / class / method is redefined. This message belongs to the basic checker.

E0103:

Used when break or continue keywords are used outside a loop. This message belongs to the basic checker.

4. Design

4.1. Description

checks for sign of poor/misdesign: * number of methods, attributes, local variables... * size, complexity of functions, methods

4.2. Messages

R0901:

Used when class has too many parent classes. This message belongs to the design checker.

R0902:

Used when class has too many instance attributes. This message belongs to the design checker.

R0903:

Used when class has not enough public methods. This message belongs to the design checker.

R0904:

Used when class has too many public methods. This message belongs to the design checker.

R0911:

Used when a function or method has too many return statement. This message belongs to the design checker.

R0912:

Used when a function or method has too many branches. This message belongs to the design checker.

R0913:

Used when a function or method takes too many arguments. This message belongs to the design checker.

R0914:

Used when a function or method has too many local variables. This message belongs to the design checker.

R0915:

Used when a function or method has too many statements. You should then split it in smaller functions / methods. This message belongs to the design checker.

R0921:

Used when an abstract class is not used as ancestor anywhere. This message belongs to the design checker.

R0922:

Used when an abstract class is used less than X times as ancestor. This message belongs to the design checker.

R0923:

Used when an interface class is not implemented anywhere. This message belongs to the design checker.

5. Imports

5.1. Description

checks for * external modules dependencies * relative / wildcard imports * cyclic imports * uses of deprecated modules

This checker also defines the following reports: * R0401: External dependencies * R0402: Modules dependencies graph

5.2. Messages

R0401:

Used when a cyclic import between two or more modules is detected. This message belongs to the imports checker.

W0401:

Used when from module import * is detected. This message belongs to the imports checker.

W0402:

Used a module marked as deprecated is imported. This message belongs to the imports checker.

W0403:

Used when an import relative to the package directory is detected. This message belongs to the imports checker.

W0404:

Used when a module is reimported multiple times. This message belongs to the imports checker.

W0406:

Used when a module is importing itself. This message belongs to the imports checker.

F0401:

Used when pylint has been unable to import a module. This message belongs to the imports checker.

6. Classes

6.1. Description

checks for : * methods without self as first argument * overriden methods signature * access only to existant members via self * attributes not defined in the __init__ method * supported interfaces implementation * unreachable code

6.2. Messages

W0201:

Used when an instance attribute is defined outside the __init__ method. This message belongs to the classes checker.

W0211:

Used when a static method has "self" or "cls" as first argument. This message belongs to the classes checker.

W0221:

Used when a method has a different number of arguments than in the implemented interface or in an overriden method. This message belongs to the classes checker.

W0222:

Used when a method signature is different than in the implemented interface or in an overriden method. This message belongs to the classes checker.

W0223:

Used when an abstract method (ie raise NotImplementedError) is not overriden in concrete class. This message belongs to the classes checker.

W0231:

Used when an ancestor class method has an __init__ method which is not called by a derived class. This message belongs to the classes checker.

W0232:

Used when a class has no __init__ method, neither its parent classes. This message belongs to the classes checker.

W0233:

Used when an __init__ method is called on a class which is not in the direct ancestors for the analysed class. This message belongs to the classes checker.

E0201:

Used when an instance member not defined in the instance, its class or its ancestors is accessed. This message belongs to the classes checker.

E0202:

Used when a class defines a method which hide an attribute from an ancestor class. This message belongs to the classes checker.

E0203:

Used when an instance member is accessed before it's actually assigned. This message belongs to the classes checker.

E0211:

Used when a method which should have the bound instance as first argument has no argument defined. This message belongs to the classes checker.

E0212:

Used when a class method has an attribute different than "cls" as first argument, to easily differentiate them from regular instance methods. This message belongs to the classes checker.

E0213:

Used when a method has an attribute different the "self" as first argument. This message belongs to the classes checker.

E0214:

Used when a metaclass method has an attribute different the "mcs" as first argument. This message belongs to the classes checker.

E0221:

Used when a class claims to implement an interface which is not a class. This message belongs to the classes checker.

E0222:

Used when a method declared in an interface is missing from a class implementing this interface This message belongs to the classes checker.

F0201:

Used when PyLint has been unable to fetch a method declared in an interface (either in the class or in the interface) and so to check its implementation. This message belongs to the classes checker.

F0202:

Used when PyLint has been unable to check methods signature compatibility for an unexpected raison. Please report this kind if you don't make sense of it. This message belongs to the classes checker.

F0203:

Used when PyLint has been unable to resolve a name. This message belongs to the classes checker.

7. Exceptions

7.1. Description

checks for * excepts without exception filter * string exceptions

7.2. Messages

W0701:

Used when a string exception is raised. This message belongs to the exceptions checker.

W0702:

Used when an except clause doesn't specify exceptions type to catch. This message belongs to the exceptions checker.

W0703:

Used when an except catch Exception instances. This message belongs to the exceptions checker.

W0704:

Used when an except clause does nothing but "pass" and there is no "else" clause. This message belongs to the exceptions checker.

W0705:

Used when except clauses are not in the correct order (from the more specific to the more generic). This message belongs to the exceptions checker.

W0706:

Used when a variable used to raise an exception is initially assigned to a value which can't be used as an exception. This message belongs to the exceptions checker.

8. Metrics

8.1. Description

does not check anything but gives some raw metrics : * total number of lines * total number of code lines * total number of docstring lines * total number of comments lines * total number of empty lines

This checker also defines the following reports: * R0701: Raw metrics

9. Miscellaneous

9.1. Description

checks for: * warning notes in the code like FIXME, XXX * PEP 263: source code with non ascii character but no encoding declaration

9.2. Messages

W0511:

Used when a warning note as FIXME or XXX is detected. This message belongs to the miscellaneous checker.

E0501:

Used when some non ascii characters are detected but now encoding is specified, as explicited in the PEP 263. This message belongs to the miscellaneous checker.

E0502:

Used when a known encoding is specified but the file doesn't seem to be actually in this encoding. This message belongs to the miscellaneous checker.

E0503:

Used when an encoding is specified, but it's unknown to Python. This message belongs to the miscellaneous checker.

10. Format

10.1. Description

checks for : * unauthorized constructions * strict indentation * line length * use of <> instead of !=

10.2. Messages

C0301:

Used when a line is longer than a given number of characters. This message belongs to the format checker.

C0321:

Used when more than on statement are found on the same line. This message belongs to the format checker.

C0322:

Used when one of the following operator (!= | <= | == | >= | < | > | = | += | -= | *= | /= | %) is not preceded by a space. This message belongs to the format checker.

C0323:

Used when one of the following operator (!= | <= | == | >= | < | > | = | += | -= | *= | /= | %) is not followed by a space. This message belongs to the format checker.

C0324:

Used when a comma (",") is not followed by a space. This message belongs to the format checker.

W0302:

Used when a module has too much lines, reducing its readibility. This message belongs to the format checker.

W0311:

Used when an unexpected number of indentation's tabulations or spaces has been found. This message belongs to the format checker.

W0312:

Used when there are some mixed tabs and spaces in a module. This message belongs to the format checker.

W0331:

Used when the <> operator is used instead of !=. This message belongs to the format checker.

W0332:

Used when a lower case "l" is used to mark a long integer. You should use a upper case "L" since the letter "l" looks too much like the digit "1" This message belongs to the format checker.

F0321:

Used when an unexpected error occured in bad format detection. Please report the error if it occurs. This message belongs to the format checker.

11. Similarities

11.1. Description

checks for similarities and duplicated code. This computation may be memory / CPU intensive, so you should disable it if you experiments some problems.

This checker also defines the following reports: * R0801: Duplication

11.2. Messages

R0801:

Indicates that a set of similar lines has been detected among multiple file. This usually means that the code should be refactored to avoid this duplication. This message belongs to the similarities checker.