Pylint output

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

Moreover 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
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 new default format:

    {C}:{line:3d},{column:2d}: {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}
    

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:

  • [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 -rn.

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

Also, a global evaluation for the code is computed.