Class: Cuprum::Operation

Inherits:

Command

• Object
• Command
• Cuprum::Operation

Includes:

Mixin

Defined in:

lib/cuprum/operation.rb

Overview

Functional object with syntactic sugar for tracking the last result.

An Operation is like a Command, but with two key differences. First, an Operation retains a reference to the result object from the most recent time the operation was called and delegates the methods defined by Cuprum::Result to the most recent result. This allows a called Operation to replace a Cuprum::Result in any code that expects or returns a result. Second, the #call method returns the operation instance, rather than the result itself.

These two features allow developers to simplify logic around calling and using the results of operations, and reduce the need for boilerplate code (particularly when using an operation as part of an existing framework, such as inside of an asynchronous worker or a Rails controller action).

Like a Command, an Operation can be defined directly by passing an implementation block to the constructor or by creating a subclass that overwrites the #process method.

Examples:

def create
  operation = CreateBookOperation.new.call(book_params)

  if operation.success?
    redirect_to(operation.value)
  else
    @book = operation.value

    render :new
  end # if-else
end # create

See Also:

• Command

Defined Under Namespace

Modules: Mixin

Instance Method Summary

• #call(*arguments, **keywords) { ... } ⇒ Cuprum::Operation

  Executes the logic encoded in the constructor block, or the #process method if no block was passed to the constructor, and returns the operation object.

• #called? ⇒ Boolean

  True if the operation has been called and has a reference to the most recent result; otherwise false.

• #error ⇒ Object

  The error (if any) from the most recent result, or nil if the operation has not been called.

• #failure? ⇒ Boolean

  True if the most recent result had an error, or false if the most recent result had no error or if the operation has not been called.

• #reset! ⇒ Object

  Clears the reference to the most recent call of the operation, if any.

• #result ⇒ Cuprum::Result

  The result from the most recent call of the operation.

• #success? ⇒ Boolean

  True if the most recent result had no error, or false if the most recent result had an error or if the operation has not been called.

• #to_cuprum_result ⇒ Object
• #value ⇒ Object

  The value of the most recent result, or nil if the operation has not been called.

Methods included from Mixin

#status

Methods inherited from Command

#initialize

Methods included from Chaining

#chain, #chain!, #tap_result, #tap_result!, #yield_result, #yield_result!

Methods included from Processing

#arity, #process

Constructor Details

This class inherits a constructor from Cuprum::Command

Instance Method Details

#call(*arguments, **keywords) { ... } ⇒ Cuprum::Operation

Executes the logic encoded in the constructor block, or the #process method if no block was passed to the constructor, and returns the operation object.

Yields:

• If a block argument is given, it will be passed to the implementation.

See Also:

• Command#call

# File 'lib/cuprum/operation.rb', line 137

#called? ⇒ Boolean

# File 'lib/cuprum/operation.rb', line 140

#error ⇒ Object

# File 'lib/cuprum/operation.rb', line 143

#failure? ⇒ Boolean

# File 'lib/cuprum/operation.rb', line 146

#reset! ⇒ Object

Clears the reference to the most recent call of the operation, if any. This allows the result and any referenced data to be garbage collected. Use this method to clear any instance variables or state internal to the operation (an operation should never have external state apart from the last result).

If the operation cannot be run more than once, this method should raise an error.

# File 'lib/cuprum/operation.rb', line 149

#result ⇒ Cuprum::Result

# File 'lib/cuprum/operation.rb', line 152

#success? ⇒ Boolean

# File 'lib/cuprum/operation.rb', line 155

#to_cuprum_result ⇒ Object

# File 'lib/cuprum/operation.rb', line 158

#value ⇒ Object

# File 'lib/cuprum/operation.rb', line 161