cogito 1.7.0

Cognitive Complexity code metric for D

To use this package, run the following command in your project's root directory:

Manual usage
Put the following dependency into your project's dependences section:

CI License


cōgitō analyses D code and calculates its [cognitive complexity].

Installing and usage

Run make install build/release/bin/cogito.

It will download and install the frontend and build a binary. Then you can run it on some D source:

Run ./build/release/bin/cogito src/main.d.

Example output

module app: 5 (src/main.d)
accumulateResult: 5 (src/main.d:9)
accumulateResult.(λ): 0 (src/main.d:12)
accumulateResult.(λ): 2 (src/main.d:16)
(λ): 0 (src/main.d:33)

Command line options

Property nameAllowed valuesDescription
--thresholdPositive numbersFail if the source score exceeds this threshold.
--aggregate-thresholdPositive numbersFail if an aggregate score exceeds this threshold.
--module-thresholdPositive numbersFail if a function score exceeds this threshold.
--formatflat, verbose, debug and silentSee below.
--configstringConfiguration file.
--helpShow a help message.


Flat format outputs only the functions violating a limit. If no limits are set, it prints all functions with their source file name and line number.

Verbose is the same as flat but it always prints all scores.

Debug output adds column numbers and scores inside aggregates.

Silent format produces no output, but returns an error if one of the thresholds is exceeded.


A configuration file can be used to specify different scores for specific modules. The configuration is a list of modules names in brackets with the corresponding score, followed by symbol specifications in this module. For example:

[cogito.list = 123]
MyStruct = 12
MyStruct.f = 8

[cogito.meter = 32]

If an element doesn't exceed the normal score, but there is a configuration for it, it also causes an error, because the configuration in this case should be removed.

The default configuration file is cogito.conf. Another file name can be specified with --config command line option. Set --config to - to read from the standard input.

Return codes

The return code of the program provides some information on what kind of error occurred.

  • 0: Success
  • 1: Command line arguments are invalid
  • 2: Some source files contain errors
  • 3: Function threshold violation
  • 4: Aggregate threshold violation
  • 5: Module threshold violation
  • 6: Redundant threshold configuration found
  • Eugen Wissner
1.7.0 2023-May-16
1.6.0 2023-Mar-15
1.5.0 2023-Mar-09
1.4.1 2023-Mar-08
1.4.0 2022-Jun-10
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