Class: NRSER::Message

Inherits:
Object
  • Object
show all
Defined in:
lib/nrser/message.rb

Overview

Container for a message (method call) to be sent to a receiver via Object#send (or Object#public_send).

Encapsulates the method symbol as well as any arguments and block to send.

Implements ‘#to_proc` so it can be used like

enum.map &message

You can invoke the message on a receiver object like

msg.send_to obj

Useful for clearly describing and recognizing data that is meant to be sent to an object as a method call, especially in testing.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(symbol, *args, &block) ⇒ Message

Construct a new message.

Parameters:

  • symbol (String | Symbol) —

    Name of target method.

  • *args (Array) —

    Any arguments that should be sent.

  • &block (nil | #call) —

    Optional block that should be sent.



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# File 'lib/nrser/message.rb', line 85

def initialize symbol, *args, &block
  @symbol = symbol
  @args = args
  @block = block
end

Instance Attribute Details

#args ⇒ Array (readonly)

Arguments (parameters). May be empty.

Returns:

  • (Array) 


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# File 'lib/nrser/message.rb', line 64

def args
  @args
end

#block ⇒ nil | #call (readonly)

Optional block to send to the receiver.

Returns:

  • (nil | #call) 


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# File 'lib/nrser/message.rb', line 71

def block
  @block
end

#symbol ⇒ Symbol | String (readonly)

Name of method the message is for.

Returns:

  • (Symbol | String) 


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# File 'lib/nrser/message.rb', line 57

def symbol
  @symbol
end

Class Method Details

.from(symbol, *args, &block) ⇒ NRSER::Message .from(message) ⇒ NRSER::Message

Instantiate a message from the arguments, unless they already are one.

Overloads:

  • .from(symbol, *args, &block) ⇒ NRSER::Message

    Create a new instance from the arguments by passing them to new.

    Parameters:

    • message (NRSER::Message) —

      An already instantiated message, which is simple returned.

    Returns:

  • .from(message) ⇒ NRSER::Message

    Convenience method to return the message if it’s the only argument.

    Parameters:

    • message (NRSER::Message) —

      An already instantiated message, which is simple returned.

    Returns:



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# File 'lib/nrser/message.rb', line 44

def self.from *args, &block
  if args.length == 1 && args[0].is_a?( Message )
    args[0]
  else
    new *args, &block
  end
end

Instance Method Details

#send_to(receiver, publicly: true) ⇒ Object

Send this instance to a receiver object.

Examples:


msg.send_to obj

Parameters:

  • receiver (Object) —

    Object that the message will be sent to.

  • publicly: (Boolean) (defaults to: true) —

    When ‘true`, the message will be sent via Object#public_send. This is the default behavior.

    When ‘false`, the message will be sent via Object#send, allowing it to invoke private and protected methods on the receiver.

Returns:

  • (Object) —

    Result of the method call.



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# File 'lib/nrser/message.rb', line 138

def send_to receiver, publicly: true
  if publicly
    receiver.public_send symbol, *args, &block
  else
    receiver.send symbol, *args, &block
  end
end

#to_proc(publicly: true) ⇒ Proc Also known as: to_sender

Creates a Proc that accepts a single ‘receiver` argument and calls #sent_to on it, allowing messages to be used via the `&` operator in `map`, etc.

Examples:

Map each entry as the message receiver using ‘&`


enum = [ [], [1], [1, 2] ]

length_message = NRSER::Message.new :length
first_message = NRSER::Message.new :first

enum.map &length_message
# => [0, 1, 2]

enum.map &first_message
# => [nil, 1, 1]

Returns:

  • (Proc) 


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# File 'lib/nrser/message.rb', line 111

def to_proc publicly: true
  # block
  ->( receiver ) { send_to receiver, publicly: publicly }
end

#to_s ⇒ String

Returns Brief description of the message.

Returns:

  • (String) —

    Brief description of the message.



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# File 'lib/nrser/message.rb', line 149

def to_s
  "#<NRSER::Message symbol=#{ symbol } args=#{ args } block=#{ block }>"
end