Class: RuboCop::Cop::Style::SymbolProc

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
AllowedMethods, AllowedPattern, CommentsHelp, RangeHelp
Defined in:
lib/rubocop/cop/style/symbol_proc.rb

Overview

Use symbols as procs when possible.

If you prefer a style that allows block for method with arguments, please set true to AllowMethodsWithArguments. define_method? methods are allowed by default. These are customizable with AllowedMethods option.

Examples:

# bad
something.map { |s| s.upcase }
something.map { _1.upcase }

# good
something.map(&:upcase)

AllowMethodsWithArguments: false (default)

# bad
something.do_something(foo) { |o| o.bar }

# good
something.do_something(foo, &:bar)

AllowMethodsWithArguments: true

# good
something.do_something(foo) { |o| o.bar }

AllowComments: false (default)

# bad
something.do_something do |s| # some comment
  # some comment
  s.upcase # some comment
  # some comment
end

AllowComments: true

# good  - if there are comment in either position
something.do_something do |s| # some comment
  # some comment
  s.upcase # some comment
  # some comment
end

AllowedMethods: [define_method] (default)

# good
define_method(:foo) { |foo| foo.bar }

AllowedPatterns: [] (default)

# bad
something.map { |s| s.upcase }

AllowedPatterns: ['map'] (default)

# good
something.map { |s| s.upcase }

Cop Safety Information:

  • This cop is unsafe because there is a difference that a Proc generated from Symbol#to_proc behaves as a lambda, while a Proc generated from a block does not. For example, a lambda will raise an ArgumentError if the number of arguments is wrong, but a non-lambda Proc will not.

    For example:

    class Foo
  def bar
    :bar
  end
end

def call(options = {}, &block)
  block.call(Foo.new, options)
end

call { |x| x.bar }
#=> :bar
call(&:bar)
# ArgumentError: wrong number of arguments (given 1, expected 0)

Constant Summary collapse

MSG = 
'Pass `&:%<method>s` as an argument to `%<block_method>s` instead of a block.'
SUPER_TYPES = 
%i[super zsuper].freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Class Method Summary collapse

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods included from CommentsHelp

#comments_contain_disables?, #comments_in_range, #contains_comments?, #source_range_with_comment

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Class Method Details

.autocorrect_incompatible_with ⇒ Object 



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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 111

def self.autocorrect_incompatible_with
  [Layout::SpaceBeforeBlockBraces]
end

Instance Method Details

#destructuring_block_argument?(argument_node) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 136

def destructuring_block_argument?(argument_node)
  argument_node.one? && argument_node.source.include?(',')
end

#on_block(node) ⇒ Object Also known as: on_numblock

rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity



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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 116

def on_block(node)
  symbol_proc?(node) do |dispatch_node, arguments_node, method_name|
    # TODO: Rails-specific handling that we should probably make
    # configurable - https://github.com/rubocop/rubocop/issues/1485
    # we should allow lambdas & procs
    return if proc_node?(dispatch_node)
    return if unsafe_hash_usage?(dispatch_node)
    return if unsafe_array_usage?(dispatch_node)
    return if %i[lambda proc].include?(dispatch_node.method_name)
    return if allowed_method_name?(dispatch_node.method_name)
    return if allow_if_method_has_argument?(node.send_node)
    return if node.block_type? && destructuring_block_argument?(arguments_node)
    return if allow_comments? && contains_comments?(node)

    register_offense(node, method_name, dispatch_node.method_name)
  end
end

#proc_node?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 98

def_node_matcher :proc_node?, '(send (const {nil? cbase} :Proc) :new)'

#symbol_proc?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 104

def_node_matcher :symbol_proc?, <<~PATTERN
  {
    (block $#symbol_proc_receiver? $(args (arg _var)) (send (lvar _var) $_))
    (numblock $#symbol_proc_receiver? $1 (send (lvar :_1) $_))
  }
PATTERN

#symbol_proc_receiver?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 101

def_node_matcher :symbol_proc_receiver?, '{(call ...) (super ...) zsuper}'