Pylint output

Output options

Output by default is written to stdout. The simplest way to output to a file is with the --output=<filename> option.

The default format for the output is raw text. You can change this by passing pylint the --output-format=<value> option. Possible values are: text, json, parseable, colorized and msvs (for Visual Studio).

Multiple output formats can be used at the same time by passing a comma-separated list of formats to --output-format. This output can be redirected to a file by giving a filename after a colon.

For example, to save a json report to somefile.json and print a colorized report to stdout at the same time:

--output-format=json:somefile.json,colorized

Custom message formats

You can customize the exact way information are displayed using the --msg-template=<format string> option. The format string uses the Python new format syntax and the following fields are available :

path

relative path to the file

abspath

absolute path to the file

line

line number

column

column number

end_line

line number of the end of the node

end_column

column number of the end of the node

module

module name

obj

object within the module (if any)

msg

text of the message

msg_id

the message code (eg. I0011)

symbol

symbolic name of the message (eg. locally-disabled)

C

one letter indication of the message category

category

fullname of the message category

For example, the former (pre 1.0) default format can be obtained with:

pylint --msg-template='{msg_id}:{line:3d},{column}: {obj}: {msg}'

A few other examples:

  • the default format:

    {path}:{line}:{column}: {msg_id}: {msg} ({symbol})

  • Visual Studio compatible format (former 'msvs' output format):

    {path}({line}): [{msg_id}{obj}] {msg}

  • Parseable (Emacs and all, former 'parseable' output format) format:

    {path}:{line}: [{msg_id}({symbol}), {obj}] {msg}

The --msg-template option can only be combined with text-based reporters (--output-format either unspecified or one of: parseable, colorized or msvs). If both --output-format and --msg-template are specified, the --msg-template option will take precedence over the default line format defined by the reporter class.

If end_line or end_column are None, they will be represented as an empty string by the default TextReporter.

Source code analysis section

For each python module, Pylint will first display a few '*' characters followed by the name of the module. Then, a number of messages with the following format:

MESSAGE_TYPE: LINE_NUM:[OBJECT:] MESSAGE

You can get another output format, useful since it's recognized by most editors or other development tools using the --output-format=parseable option.

The message type can be:

  • [I]nformational messages that Pylint emits (do not contribute to your analysis score)

  • [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

Sometimes the line of code which caused the error is displayed with a caret pointing to the error. This may be generalized in future versions of Pylint.

Example (extracted from a run of Pylint on itself...):

************* Module pylint.checkers.format
W: 50: Too long line (86/80)
W:108: Operator not followed by a space
     print >>sys.stderr, 'Unable to match %r', line
            ^
W:141: Too long line (81/80)
W: 74:searchall: Unreachable code
W:171:FormatChecker.process_tokens: Redefining built-in (type)
W:150:FormatChecker.process_tokens: Too many local variables (20/15)
W:150:FormatChecker.process_tokens: Too many branches (13/12)

Reports section

Following the analysis message, Pylint can display a set of reports, each one focusing on a particular aspect of the project, such as number of messages by categories, modules dependencies. These features can be enabled through the --reports=y option, or its shorthand version -ry.

For instance, the metrics report displays summaries gathered from the current run.

  • the number of processed modules

  • for each module, the percentage of errors and warnings

  • the total number of errors and warnings

  • percentage of classes, functions and modules with docstrings, and a comparison from the previous run

  • percentage of classes, functions and modules with correct name (according to the coding standard), and a comparison from the previous run

  • a list of external dependencies found in the code, and where they appear

Score section

Finally, Pylint displays a global evaluation score for the code, rated out of a maximum score of 10.0. This output can be suppressed through the --score=n option, or its shorthand version -sn.

The evaluation formula can be overridden with the --evaluation=<python_expression> option.