Class: Arrow::Template::RenderingScope

Inherits:
Object
  • Object
show all
Defined in:
lib/arrow/template.rb

Overview

A class for objects which contain the execution space of all the code in a single rendering of a template.

Instance Method Summary collapse

Methods inherited from Object

deprecate_class_method, deprecate_method, inherited

Constructor Details

#initialize(defs = {}) ⇒ RenderingScope

Create a new RenderingScope object with the specified definitions defs. Each key => value pair in defs will become singleton accessors on the resulting object.



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# File 'lib/arrow/template.rb', line 78

def initialize( defs={} )
	@definitions = []
	self.add_definition_set( defs )
end

Instance Method Details

#add_definition_set(defs) ⇒ Object

Add the specified definitions defs to the object.



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# File 'lib/arrow/template.rb', line 97

def add_definition_set( defs )
	# self.log.debug "adding definition set: %p" % [ defs ]
	@definitions.push( defs )

	defs.each do |name,val|
		raise Arrow::ScopeError, "Cannot add a definition with a blank key" if
			name.to_s.empty?
		raise Arrow::ScopeError, "Cannot override @definitions" if
			name == 'definitions'
		@definitions.last[ name ] = val

		# Add accessor and ivar for the definition if it doesn't
		# already have one.
		unless self.respond_to?( name.to_s.to_sym )
			#self.log.debug "Adding accessor for %s" % name
			(class << self; self; end).instance_eval {
				attr_accessor name.to_s.to_sym
			}
		else
			#self.log.debug "Already have an accessor for '#{name}'"
		end

		self.instance_variable_set( "@#{name}", defs[name] )
	end
end

#get_binding ⇒ Object

Fetch the Binding object for the RenderingScope.



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# File 'lib/arrow/template.rb', line 93

def get_binding; binding; end

#override(defs) ⇒ Object

Override the given definitions defs for the duration of the given block. After the block exits, the original definitions will be restored.



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# File 'lib/arrow/template.rb', line 164

def override( defs ) # :yields: receiver
	begin
		#self.log.debug "Before adding definitions: %d scope frame/s. Last: %p" %
		#	[ @definitions.nitems, @definitions.last.keys ]
		self.add_definition_set( defs )
		#self.log.debug "After adding definitions: %d scope frame/s. Last: %p" % 
		#	[ @definitions.nitems, @definitions.last.keys ]
		yield( self )
	ensure
		self.remove_definition_set
	end
end

#remove_definition_set ⇒ Object

Remove the specified definitions defs from the object. Using a definition so removed after this point will raise an error.



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# File 'lib/arrow/template.rb', line 126

def remove_definition_set
	#self.log.debug "Removing definition set from stack of %d frames" %
	#	@definitions.nitems
	defs = @definitions.pop
	#self.log.debug "Removing defs: %p, %d frames left" % 
	#	[ defs, @definitions.nitems ]

	defs.keys.each do |name|
		next if name == 'definitions'

		# If there was already a definition in effect with the same
		# name in a previous scope, fetch it so we can play with it.
		previousSet = @definitions.reverse.find {|set| set.key?(name)}
		#self.log.debug "Found previousSet %p for %s in scope stack of %d frames" %
		#	[ previousSet, name, @definitions.nitems ]

		# If none of the previous definition sets had a definition
		# with the same name, remove the accessor and the ivar
		unless previousSet
			#self.log.debug "Removing definition '%s' entirely" % name
			(class << self; self; end).module_eval {
				remove_method name.to_s.to_sym
			}
			remove_instance_variable( "@#{name}" )

		# Otherwise just reset the ivar to the previous value
		else
			#self.log.debug "Restoring previous def for '%s'" % name
			self.instance_variable_set( "@#{name}", previousSet[name] )
		end
	end

end