Module: Gamefic::Plot::Theater

Included in:
Gamefic::Plot, Subplot
Defined in:
lib/gamefic/plot/theater.rb

Instance Method Summary collapse

Instance Method Details

#stage(*args, &block) ⇒ Object

Execute a block of code in a subset of the object’s scope. An object’s stage is an isolated namespace that has its own instance variables and access to its owner’s public methods.

There are two ways to execute code on the stage. It will accept either a string of code with an optional file name and line number, or a proc with optional arguments. See module_eval and module_exec for more information.

Examples:

Evaluate a string of code

stage "puts 'Hello'"

Evaluate a string of code with a file name and line number

stage "puts 'Hello'", "file.rb", 1

Execute a block of code

stage {
  puts 'Hello'
}

Execute a block of code with arguments

stage 'hello' { |message|
  puts message # <- prints 'hello'
}

Use an instance variable

stage "@message = 'hello'"
stage "puts @message" # <- prints 'hello'

Returns:

  • (Object) —

    The value returned by the executed code



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# File 'lib/gamefic/plot/theater.rb', line 34

def stage *args, &block
  if block.nil?
    theater.module_eval *args
  else
    theater.module_exec *args, &block
  end
end

#theater ⇒ Module

The module that acts as an isolated namespace for staged code.

Returns:

  • (Module) 


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# File 'lib/gamefic/plot/theater.rb', line 45

def theater
  return @theater unless @theater.nil?
  instance = self

  @theater = Module.new do
    define_singleton_method :method_missing do |symbol, *args, &block|
      instance.public_send :public_send, symbol, *args, &block
    end

    define_singleton_method :stage do |*args|
      raise NoMethodError.new("The stage method is not available from inside staged scripts")
    end

    define_singleton_method :to_s do
      "[Theater]"
    end
  end

  # HACK: Include the theater module in Object so that classes and modules
  # defined in scripts are accessible from procs passed to the stage.
  Object.class_exec(@theater) do |t|
    include t
  end
  
  @theater
end