pg.symbolic.ValueFromParentChain

Accessible via pg.symbolic.ValueFromParentChain.

class ValueFromParentChain

Bases: pg.InferredValue

A value that could inferred from the parent chain.

For example:

class A(pg.Object):
  x: int
  y: int = pg.symbolic.ValueFromParentChain()

# Not okay: `x` is not inferential and is not specified.
A()

# Okay: both `x` and `y` are specified.
A(x=1, y=2)

# Okay: `y` is inferential, hence optional.
a = A(x=1)

# Raises: `y` is neither specified during __init__
# nor provided from the context.
a.y

d = pg.Dict(y=2, z=pg.Dict(a=a))

# `a.y` now refers to `d.a` since `d` is in its symbolic parent chain,
# aka. context.
assert a.y == 2

Methods:

infer(**kwargs)

Returns the inferred value.

Attributes:

inference_key

Returns the key for attribute inference from parents.

infer(**kwargs)

Returns the inferred value.

Return type:

Any

Parameters:

**kwargs – Optional keyword arguments for inference, which are usually inferential subclass specific.

Returns:

Inferred value.

Raises:

AttributeError – If the value cannot be inferred.

property inference_key: str

Returns the key for attribute inference from parents.