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Attribute inherited from parent

pyrefly/test_laziness/test_attribute_inherited.md

1.3.0-dev.42.5 KB
Original Source

Attribute inherited from parent

Accessing c.base_attr where base_attr is defined on Base (in module c), inherited by Child (in module b).

All necessary demands:

  • a -> b::KeyExport("Child") — resolve the import
  • a -> b::KeyClassMetadata(0) — needed to know Child's bases for MRO. Computing Child's metadata also validates class-header keywords against any inherited __init_subclass__, which walks Child's bases and re-demands Base's (already-cached) c::KeyClassMetadata.
  • b -> c::KeyExport("Base") and b -> c::KeyClassMetadata(0) — resolving Child's MRO requires knowing Base
  • a -> b::KeyClassMro(0) — compute MRO to walk ancestors
  • a -> c::KeyClassField(0, "base_attr") — the actual attribute resolution; children include the lazy builtin lookup for int
  • a -> b::KeyClassSynthesizedFields(0) and a -> c::KeyClassSynthesizedFields(0) — MRO walk checks synthesized fields on each ancestor

Superfluous:

  • a -> b::KeyAbstractClassCheck(0) — abstract checking is only relevant for instantiation, not for attribute access.

Files

a.py:

python
from b import Child
c = Child()
x = c.base_attr

b.py:

python
from c import Base
class Child(Base):
    child_attr: str = 'hello'

c.py:

python
class Base:
    base_attr: int = 1

Check a.py

expected
a: Solutions
b: Answers
c: Answers

(66 builtin demands hidden)
a -> b::Exports(is_special_export)
a -> b::Load(module_exists)
a -> b::Exports(export_exists)
a -> b::Exports(is_implicit_reexport)
a -> b::Exports(get_deprecated)
a -> b::KeyExport(Name("Child"))
  b -> c::Exports(is_special_export)
a -> b::KeyClassMetadata(ClassDefIndex(0))
  b -> c::Exports(export_exists)
  b -> c::Exports(is_implicit_reexport)
  b -> c::Exports(get_deprecated)
  b -> c::KeyExport(Name("Base"))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
a -> b::KeyClassMetadata(ClassDefIndex(0))
a -> b::KeyAbstractClassCheck(ClassDefIndex(0))
  b -> c::KeyAbstractClassCheck(ClassDefIndex(0))
a -> b::KeyClassSynthesizedFields(ClassDefIndex(0))
a -> b::KeyClassMro(ClassDefIndex(0))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
  b -> c::KeyClassMetadata(ClassDefIndex(0))
  b -> c::KeyClassBaseType(ClassDefIndex(0))
  b -> c::KeyClassMro(ClassDefIndex(0))
a -> c::KeyClassSynthesizedFields(ClassDefIndex(0))
a -> b::KeyClassMro(ClassDefIndex(0))
a -> c::KeyClassField(ClassDefIndex(0), Name("base_attr"))