Object

All data that can be assigned to a variable. The Object class has the following attributes.

. __repr__: returns a (non-rich) string representation of the object.
. __sizeof__: returns the size of the object (including heap allocation).
. __dir__: return a list of attributes of the object.
. __hash__: return the hash value of the object.
. __getattribute__: retrieve and return an object's attributes * `.
.clone: create and return a clone of an object (an independent entity in memory).
.copy: return a copy of an object (identical in memory).

Record

An object created by a record literal ({attr = value; ...}). This object can be a .clone or a . __sizeof__ and other basic methods.

obj = {.x = 1}
assert obj.x == 1

obj2 = {. .x; .y = 2}
assert obj2.x == 1 and obj2.y == 2

Attribute

An object associated with an object. In particular, a subroutine attribute that takes itself (self) as its implicit first argument is called a method.

# Note that private_attr does not have `. Note that there is no `.
record = {.public_attr = j; private_attr = 2; .method = self -> self.i + 1}
record.public_attr == 2
record.private_attr # AttributeError: private_attr is private
assert record.method() == 3

Element

An object belonging to a specific type (e.g. 1 is an element of type Int). All objects are at least {=} type. In the case of an element of a class, it is sometimes called an instance.

Subroutine

An object that is an instance of a function or procedure (including methods). The class representing a subroutine is Subroutine. More generally, .__call__ is called a Callable.

Callable

Object that implements .__call__. Superclass of Subroutine.

Type

An object that defines required attributes and makes objects common. There are two main types: polymorphic type and monomorphic type. Typical monomorphic types are Int, Str, etc. Polymorphic types include Option Int, [Int; 3] and so on. In addition, types that define methods to change the state of an object are called mutable types, and require variable attributes marked with ! (e.g., dynamic arrays: [T; !_]).

Function

Subroutines that have read permission for external variables (excluding static variables) but do not have read/write permission for external variables. In other words, it has no external side effects. Erg functions are defined differently than Python because they do not allow side effects.

Procedure

It has read and self permissions for external variables, read/write permissions for static variables, and is allowed to use all subroutines. It can have external side effects.

Method

A subroutine that implicitly takes self as the first argument. It is a different type than a simple function/procedure.

Entity

Objects that are not subroutines and types. Monomorphic entities (1, "a", etc.) are also called value objects, and polymorphic entities ([1, 2, 3], {"a": 1}) are also called container objects.

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