1.25.3 Get methods

class <-convert: any -> class

Converts a class-name or type object of type<-kind into a class object. If a class does not exist and the argument is a name, the pce->exception with context argument the name of the required class is generated. This mechanism is used by the autoloader (pce_autoload/2).

See also

- pce->exception
- class<-instance

class <-send_method: name -> behaviour

class <-get_method: name -> behaviour

Resolve a selector name to its implementation. The returned value is either a method object or a variable. These methods operate at the class level. The methods object<-get_method and object<-send_method operate at the object level and take care of object-level defined behaviour as well as delegation.

See also object->has_get_method and object<-get_method.

class <-instance: argument=unchecked ... -> object

Create an instance of this class. Creating an instance entails the following steps:

• Memory is allocated for the instance. All slots are filled with variable<-alloc_value of the corresponding variable object.
• If it concerns a global object, a named reference is created.
• if the class has instance variables with non-constant initial value or a function as initial value (see variable -initial_value), execute these funcions and assign the slot values.
• The PCE virtual machine invokes object->initialise to the new object with the arguments given to this method.
• If object->initialise fails, the exception initialise_failed is raised using pce->exception. The context parameter is the (incomplete) object reference.
• If class->initialise succeeds, class<-instance returns the new object.

  NOTE: pce<-instance is an alternative for creating objects. This gate has two advantages: type conversion allows you to specify the class-name rather than the class, and -if the class does not yet exist-, an exception is raised allowing the class autoloading to create it. See also class create and new/2

  See also

  - class<-convert
  - pce->exception
  - object->initialise
  - variable-initial_value
  - pce<-instance
  - class-created_messages

class <-instance_variable: name|int -> variable

Resolve the variable object from the named instance variable or the offset (1-based) of the variable. See also class<-instance_variables, class<-send_method or class<-get_method.

class <-lookup: name=name, super=[class] -> class

Lookup the name of the class in the hash_table object @classes. If super is specified, class<-lookup verifies the super and generates an error message on a mismatch. This method ensures that

?- get(class(point), instance, 4, 5, P).

Actually returns an instance of the existing class point instead of returning an instance of a new class named point.

class <-no_freed: sub_too=[bool] -> int

How many instances of this class were freed. If subtoo is @on the freed instances of class<-sub_classes are added. See also class<-no_created.

class <-super_class_name: -> name

Inherits description from: class-sub_classes