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Configuration

DCM is designed to be flexible and configurable for your use case. You can turn off every rule and run only with enabled metrics calculation or have both rules and metrics enabled.

To configure DCM, add a dart_code_metrics entry to analysis_options.yaml:

analysis_options.yaml
dart_code_metrics:
  exclude-public-api: # configures the "exclude-public-api" mode for the commands that use it
  extends:
    - ... # configures the list of preset configurations
  exclude:
    rules:
      - ... # configures the list of files that should be ignored by rules
    metrics:
      - ... # configures the list of files that should be ignored by metrics
    unused-code:
      - ... # configures the list of files that should be ignored by unused code checks
    unused-files:
      - ... # configures the list of files that should be ignored by unused files checks
    parameters:
      - ... # configures the list of files that should be ignored by parameters checks
  formatter:
    - ... # configures the formatter
  assists:
    - ... # configures the list of assists
  metrics:
    - ... # configures the list of reported metrics
  pubspec-rules:
    - ... # configures the list of rules for pubspec.yaml
  rules:
    - ... # configures the list of rules
note

This configuration is used by both CLI and the analysis server.

Basic config example:

analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name
    - avoid-collapsible-if
    - avoid-redundant-else
    - avoid-incomplete-copy-with
    - avoid-self-compare
    - avoid-self-assignment
    - avoid-unnecessary-nullable-return-type
    - avoid-unrelated-type-casts
    - prefer-declaring-const-constructor
info

You can find a list of recommended rules here.

Basic config with metrics:

analysis_options.yaml
dart_code_metrics:
  metrics:
    cyclomatic-complexity: 20
    number-of-parameters: 4
    maximum-nesting-level: 5
  exclude:
    metrics:
      - test/**
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name
    - avoid-collapsible-if
    - avoid-redundant-else
    - avoid-incomplete-copy-with
    - avoid-self-compare
    - avoid-self-assignment
    - avoid-unnecessary-nullable-return-type
    - avoid-unrelated-type-casts
    - prefer-declaring-const-constructor
info

You can find a list of recommended metrics here.

Custom analysis_option Files​

Aside from the regular analysis_option.yaml file, you can add a custom config file that matches one of the given patterns

  • starts with analysis_options (e.g. analysis_options.1.1.0.yaml)
  • starts with dcm (e.g. dcm_config.yaml or dcm.yaml)
  • placed inside a folder called dcm (e.g. dcm/config.yaml)

If such a file is referenced by any analysis_option.yaml file, DCM will correctly update configuration changes, validate rule names and display a configuration icon (⚙️) for configurable rules.

However, unlike for regular analysis_options.yaml files, code actions are not available.

IDE Autocompletion (VS Code only)​

To enable autocompletion for DCM configuration, modify the settings.json to the following:

.vscode/settings.json
{
  "[yaml]": {
    "editor.quickSuggestions": {
      "strings": "on"
    }
  }
}

Excluding Public API​

For commands that can affect the package's public API ("Check Unused Code", "Check Unused Files" and "Check Parameters"), setting the exclude-public-api entry in the analysis_options.yaml file will override the --exclude-public-api CLI option.

For example, if publicly exported files of a particular package are not expected to be changed, setting the exclude-public-api entry to true and running the command will exclude the public API only for that particular package.

analysis_options.yaml
dart_code_metrics:
  exclude-public-api: true # excludes public API for a particular package

Next Steps​