C3-linearization.edh

# https://en.wikipedia.org/wiki/C3_linearization

# %%

class O pass

class A extends O

class B extends O

class C extends O

class D extends O

class E extends O

class K1 extends ( A, B, C )

class K2 extends ( D, B, E )

class K3 extends ( D, A )

class Z extends ( K1, K2, K3 )

# %%
Z.mro

# unlike other object systems (e.g. in Python), where all member attributes
# (including methods) collapse into a single end object instance, in Edh an
# object is composed of a self instance and all super object instances
# strictly corresponding to mro of its class, and each such super instance
# satisfies the same rule if viewed alone, while at the same time shared
# super class induces shared object, there'll be no duplication of super
# instances.

# %%
z = Z()
supers( z )

# %%
# a specific super instance can be obtained via pattern matching:
case z of { { K2: k2 } } -> k2

# %%
# check a super instance alone
K2.mro
# %%
supers( k2 )

# %%
# check a super instance shared
{
  (
    case z of { { O: z's'o } } -> z's'o
  ) is (
    case k2 of { { O: k2's'o } } -> k2's'o
  )
}