class Reek::SmellDetectors::UtilityFunction
A Utility Function is any instance method that has no dependency on the state of the instance.
Currently UtilityFunction
will warn about any method that:
-
is non-empty, and
-
does not override an inherited method, and
-
calls at least one method on another object, and
-
doesn’t use any of self’s instance variables, and
-
doesn’t use any of self’s methods
A Utility Function often arises because it must manipulate other objects (usually its arguments) to get them into a useful form; one force preventing them (the arguments) doing this themselves is that the common knowledge lives outside the arguments, or the arguments are of too basic a type to justify extending that type. Therefore there must be something which ‘knows’ about the contents or purposes of the arguments. That thing would have to be more than just a basic type, because the basic types are either containers which don’t know about their contents, or they are single objects which can’t capture their relationship with their fellows of the same type. So, this thing with the extra knowledge should be reified into a class, and the utility method will most likely belong there.
If the method does refer to self, but refers to some other object more, FeatureEnvy
is reported instead.
See {file:docs/Utility-Function.md} for details.
Constants
- PUBLIC_METHODS_ONLY_DEFAULT
- PUBLIC_METHODS_ONLY_KEY
Public Class Methods
Source
# File lib/reek/smell_detectors/utility_function.rb, line 44 def self.default_config super.merge(PUBLIC_METHODS_ONLY_KEY => PUBLIC_METHODS_ONLY_DEFAULT) end
Reek::SmellDetectors::BaseDetector::default_config
Public Instance Methods
Source
# File lib/reek/smell_detectors/utility_function.rb, line 59 def sniff return [] if context.singleton_method? || context.module_function? return [] if context.references_self? return [] if num_helper_methods.zero? return [] if ignore_method? [smell_warning( lines: [source_line], message: "doesn't depend on instance state (maybe move it to another class?)")] end
Checks whether the given method
is a utility function.
@return [Array<SmellWarning>]
Private Instance Methods
Source
# File lib/reek/smell_detectors/utility_function.rb, line 76 def ignore_method? context.non_public_visibility? && value(PUBLIC_METHODS_ONLY_KEY, context) end
Source
# File lib/reek/smell_detectors/utility_function.rb, line 72 def num_helper_methods context.local_nodes(:send).to_a.length end