#
# Currently, Object is also used to collect all top-level methods.
interface Object
+ # Type of this instance, automatically specialized in every class
+ #
+ # A common use case of the virtual type `SELF` is to type an attribute and
+ # store another instance of the same type as `self`. It can also be used as as
+ # return type to a method producing a copy of `self` or returning an instance
+ # expected to be the exact same type as self.
+ #
+ # This virtual type must be used with caution as it can hinder specialization.
+ # In fact, it imposes strict restrictions on all sub-classes and their usage.
+ # For example, using `SELF` as a return type of a method `foo`
+ # forces all subclasses to ensure that `foo` returns the correct and updated
+ # type.
+ # A dangerous usage take the form of a method typed by `SELF` which creates
+ # and returns a new instance.
+ # If not correctly specialized, this method would break when invoked on a
+ # sub-class.
+ #
+ # A general rule for safe usage of `SELF` is to ensure that inputs typed
+ # `SELF` are stored in attributes typed `SELF` and returned by methods typed
+ # `SELF`, pretty much the same things as you would do with parameter types.
+ type SELF: Object
+
# The unique object identifier in the class.
# Unless specific code, you should not use this method.
# The identifier is used internally to provide a hash value.
fun is_same_instance(other: nullable Object): Bool is intern
# Have `self` and `other` the same value?
- ##
+ #
# The exact meaning of "same value" is let to the subclasses.
# Implicitly, the default implementation, is `is_same_instance`
fun ==(other: nullable Object): Bool do return self.is_same_instance(other)
# Have `self` and `other` different values?
- ##
+ #
# != is equivalent with "not ==".
fun !=(other: nullable Object): Bool do return not (self == other)
# The hash code of the object.
# Assuming that a == b -> a.hash == b.hash
- ##
+ #
# Without redefinition, it is based on the `object_id` of the instance.
fun hash: Int do return object_id / 8
end
# Native Booleans.
# `true` and `false` are the only instances.
+#
# Boolean are manipulated trough three special operators:
-# `and`, `or`, `not`.
+# `and`, `or`, `not`.
+#
# Booleans are mainly used by conditional statement and loops.
universal Bool
redef fun object_id is intern
redef fun -(i) is intern
redef fun *(i) is intern
redef fun /(i) is intern
+
+ # Modulo of `self` with `i`.
+ #
+ # Finds the remainder of division of `self` by `i`.
+ #
+ # assert 5 % 2 == 1
+ # assert 10 % 2 == 0
fun %(i: Int): Int is intern
redef fun zero do return 0
# The character whose ASCII value is `self`.
#
- # assert 65.ascii == 'A'
- # assert 10.ascii == '\n'
+ # assert 65.ascii == 'A'
+ # assert 10.ascii == '\n'
fun ascii: Char is intern
# Number of digits of an integer in base `b` (plus one if negative)
fun address_is_null: Bool is extern "address_is_null"
# Free the memory pointed by this pointer
- fun free `{ free(recv); `}
+ fun free is extern "free"
end