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Number of Methods (NOM)

v1.0.0
short name: NOM
effort: 10m
default threshold: 10

Number of methods is a quantitative metric that measures the total number of declared methods in a class/extension/mixin/enum/extension type.

High number of methods indicate a class with high complexity, which usually does to many things.

note

This metric does not count inherited methods that are not overridden.

Why Be Cautious​

High number of methods can lead to:

  • Difficulty in Testing: More methods can make it difficult to test all possible cases.
  • Increased Complexity: More methods can make it difficult to understand what the class does.
  • Maintainability Challenges: Large classes are harder to update, as changes may affect numerous methods.

How to Address High Number of Methods?​

First, understand the responsibility of the class. If the class is doing to many things, consider splitting it into several classes, each with a limited responsibility.

Additionally, check if all methods need to be in that particular class and consider extracting those that do not depend on state as helpers or utilities.

Config Example​

analysis_options.yaml
dcm:
  metrics:
    number-of-methods:
      threshold: 10

To set multiple threshold or other common config options, refer to the Configuring Metrics page.

Example​

info

To view what contributes to the metric value, generate an HTML report.

❌ Bad: High Number of Methods

// NOM: 12
class UserManager {
  void createUser() {}
  void updateUser() {}
  void deleteUser() {}
  void fetchUserData() {}
  void validateUser() {}
  void assignRole() {}
  void revokeRole() {}
  void sendNotification() {}
  void trackLogin() {}
  void trackLogout() {}
  void logActivity() {}
  void resetPassword() {}
}

✅ Good: Low Number of Methods

// NOM: 3
class UserManager {
  void createUser() {}
  void updateUser() {}
  void deleteUser() {}
}

// NOM: 2
class UserRoleManager {
  void assignRole() {}
  void revokeRole() {}
}

// NOM: 1
class UserNotificationManager {
  void sendNotification() {}
}

// NOM: 3
class UserActivityTracker {
  void trackLogin() {}
  void trackLogout() {}
  void logActivity() {}
}

// NOM: 1
class PasswordManager {
  void resetPassword() {}
}
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