class Ameba::Rule::Lint::UnusedExpression

• Ameba::Rule::Lint::UnusedExpression
• Ameba::Rule::Base
• Reference
• Object

Overview

A rule that disallows unused expressions.

For example, this is considered invalid:

a = obj.method do |x|
  x == 1 # => Comparison operation has no effect
  puts x
end

Float64 | StaticArray(Float64, 10)

pointerof(foo)

And these are considered valid:

a = obj.method do |x|
  x == 1
end

foo : Float64 | StaticArray(Float64, 10) = 0.1

bar = pointerof(foo)

This rule currently supports checking for unused:

• comparison operators: <, >=, etc.
• generics and unions: String?, Int32 | Float64, etc.
• literals: strings, bools, chars, hashes, arrays, range, etc.
• pseudo-method calls: sizeof, is_a? etc.
• variable access: local, @ivar, @@cvar and self

YAML configuration example:

Lint/UnusedExpression:
  Enabled: true

Included Modules

• YAML::Serializable
• YAML::Serializable::Strict

Defined in:

Constant Summary

COMPARISON_OPERATORS = ["==", "!=", "<", "<=", ">", ">=", "<=>"] of ::String

MSG_CLASS_VAR = "Class variable access is unused"

MSG_COMPARISON = "Comparison operation is unused"

MSG_GENERIC = "Generic type is unused"

MSG_INSTANCE_VAR = "Instance variable access is unused"

MSG_LITERAL = "Literal value is unused"

MSG_LOCAL_VAR = "Local variable access is unused"

MSG_PSEUDO_METHOD = "Pseudo-method call is unused"

MSG_SELF = "`self` access is unused"

MSG_UNION = "Union type is unused"

Constructors

• .new(ctx : YAML::ParseContext, node : YAML::Nodes::Node)
• .new(config = nil)

  A rule that disallows unused expressions.

Class Method Summary

• .parsed_doc : String | Nil

  Returns documentation for this rule, if there is any.

Instance Method Summary

• #description : String
• #description=(description : String)
• #enabled=(enabled : Bool)
• #enabled? : Bool
• #excluded : Array(String) | Nil
• #excluded=(excluded : Array(String) | Nil)
• #severity : Ameba::Severity
• #severity=(severity : Ameba::Severity)
• #since_version : SemanticVersion | Nil
• #since_version=(since_version : String)
• #test(source, node : Crystal::ClassVar, in_macro : Bool)
• #test(source, node : Crystal::Call, in_macro : Bool)
• #test(source, node : Crystal::Generic, in_macro : Bool)
• #test(source, node : Crystal::InstanceVar, in_macro : Bool)
• #test(source, node : Crystal::RegexLiteral, in_macro : Bool)
• #test(source, node : Crystal::BoolLiteral | Crystal::CharLiteral | Crystal::HashLiteral | Crystal::ProcLiteral | Crystal::ArrayLiteral | Crystal::RangeLiteral | Crystal::TupleLiteral | Crystal::NumberLiteral | Crystal::StringLiteral | Crystal::SymbolLiteral | Crystal::NamedTupleLiteral | Crystal::StringInterpolation, in_macro : Bool)
• #test(source, node : Crystal::Var, in_macro : Bool)
• #test(source, node : Crystal::PointerOf | Crystal::SizeOf | Crystal::InstanceSizeOf | Crystal::AlignOf | Crystal::InstanceAlignOf | Crystal::OffsetOf | Crystal::IsA | Crystal::NilableCast | Crystal::RespondsTo | Crystal::Not, in_macro : Bool)
• #test(source : Source)

  This method is designed to test the source passed in.

Constructor Detail

a = obj.method do |x|
  x == 1 # => Comparison operation has no effect
  puts x
end

Float64 | StaticArray(Float64, 10)

pointerof(foo)

a = obj.method do |x|
  x == 1
end

foo : Float64 | StaticArray(Float64, 10) = 0.1

bar = pointerof(foo)

Lint/UnusedExpression:
  Enabled: true

Class Method Detail

module Ameba
  # This is a test rule.
  # Does nothing.
  class MyRule < Ameba::Rule::Base
    def test(source)
    end
  end
end

MyRule.parsed_doc # => "This is a test rule.\nDoes nothing."

Instance Method Detail