Class: Arrow::Template::RenderingScope

Inherits:
Arrow::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

Methods inherited from Arrow::Object

deprecate_class_method, deprecate_method, inherited

Methods included from Arrow::Loggable

#log

Constructor Details

- (RenderingScope) initialize(defs = {})

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

- (Object) add_definition_set(defs)

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

- (Object) get_binding

Fetch the Binding object for the RenderingScope. 



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

def get_binding; binding end

- (Object) override(defs)

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

- (Object) remove_definition_set

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