class Puppet::Pops::Loader::Loader

Loader

A Loader is responsible for loading “entities” (“instantiable and executable objects in the puppet language” which are type, hostclass, definition, function, and bindings.

The main method for users of a Loader is the `load` or `#load_typed methods`, which returns a previously loaded entity of a given type/name, and searches and loads the entity if not already loaded.

private entities

TODO: handle loading of entities that are private. Suggest that all calls pass an origin_loader (the loader where request originated (or symbol :public). A module loader has one (or possibly a list) of what is considered to represent private loader - i.e. the dependency loader for a module. If an entity is private it should be stored with this status, and an error should be raised if the origin_loader is not on the list of accepted “private” loaders. The private loaders can not be given at creation time (they are parented by the loader in question). Another alternative is to check if the origin_loader is a child loader, but this requires bidirectional links between loaders or a search if loader with private entity is a parent of the origin_loader).

@api public

Public Instance Methods

[](typed_name) click to toggle source

Produces the value associated with the given name if defined **in this loader**, or nil if not defined. This lookup does not trigger any loading, or search of the given name. An implementor of this method may not search or look up in any other loader, and it may not define the name.

@param typed_name [TypedName] - the type, name combination to lookup

@api private

# File lib/puppet/pops/loader/loader.rb, line 64
def [] (typed_name)
  if found = get_entry(typed_name)
    found.value
  else
    nil
  end
end

find(typed_name) click to toggle source

Searches for the given name in this loader’s context (parents should already have searched their context(s) without producing a result when this method is called). An implementation of find typically caches the result.

@param typed_name [TypedName] the type, name combination to lookup @return [NamedEntry, nil] the entry for the loaded entry, or nil if not found

@api private

# File lib/puppet/pops/loader/loader.rb, line 81
def find(typed_name)
  raise NotImplementedError.new
end

get_entry(typed_name) click to toggle source

Produces a NamedEntry if a value is bound to the given name, or nil if nothing is bound.

@param typed_name [TypedName] the type, name combination to lookup @return [NamedEntry, nil] the value bound in an entry

@api private

# File lib/puppet/pops/loader/loader.rb, line 118
def get_entry(typed_name)
  raise NotImplementedError.new
end

load(type, name) click to toggle source

Produces the value associated with the given name if already loaded, or available for loading by this loader, one of its parents, or other loaders visible to this loader. This is the method an external party should use to “get” the named element.

An implementor of this method should first check if the given name is already loaded by self, or a parent loader, and if so return that result. If not, it should call `find` to perform the loading.

@param type [:Symbol] the type to load @param name [String, Symbol] the name of the entity to load @return [Object, nil] the value or nil if not found

@api public

# File lib/puppet/pops/loader/loader.rb, line 37
def load(type, name)
  if result = load_typed(TypedName.new(type, name.to_s))
    result.value
  end
end

load_typed(typed_name) click to toggle source

Loads the given typed name, and returns a NamedEntry if found, else returns nil. This the same a `load`, but returns a NamedEntry with origin/value information.

@param typed_name [TypedName] - the type, name combination to lookup @return [NamedEntry, nil] the entry containing the loaded value, or nil if not found

@api public

# File lib/puppet/pops/loader/loader.rb, line 51
def load_typed(typed_name)
  raise NotImplementedError.new
end

parent() click to toggle source

Returns the parent of the loader, or nil, if this is the top most loader. This implementation returns nil.

# File lib/puppet/pops/loader/loader.rb, line 86
def parent
  nil
end

private_loader() click to toggle source

Produces the private loader for loaders that have a one (the visibility given to loaded entities). For loaders that does not provide a private loader, self is returned.

@api private

# File lib/puppet/pops/loader/loader.rb, line 94
def private_loader
  self
end

set_entry(type, name, value, origin = nil) click to toggle source

Binds a value to a name. The name should not start with ‘::’, but may contain multiple segments.

@param type [:Symbol] the type of the entity being set @param name [String, Symbol] the name of the entity being set @param origin [URI, uri, String] the origin of the set entity, a URI, or provider of URI, or URI in string form @return [NamedEntry, nil] the created entry

@api private

# File lib/puppet/pops/loader/loader.rb, line 107
def set_entry(type, name, value, origin = nil)
  raise NotImplementedError.new
end