pg.Functor

Accessible via pg.Functor, pg.symbolic.Functor.

class Functor

Bases: pg.Object, pg.object_utils.Functor

Symbolic functions (Functors).

A symbolic function is a symbolic class with a __call__ method, whose arguments can be bound partially, incrementally bound by attribute assignment, or provided at call time.

Another useful trait is that a symbolic function is serializable, when its definition is imported by the target program and its arguments are also serializable. Therefore, it is very handy to move a symbolic function around in distributed scenarios.

Symbolic functions can be created from regular function via pg.functor:

# Create a functor class using @pg.functor decorator.
@pg.functor([
  ('a', pg.typing.Int(), 'Argument a'),
  # No field specification for 'b', which will be treated as any type.
])
def sum(a, b=1, *args, **kwargs):
  return a + b + sum(args + kwargs.values())

sum(1)()           # returns 2: prebind a=1, invoke with b=1 (default)
sum(a=1)()         # returns 2: same as above.
sum()(1)           # returns 2: bind a=1 at call time, b=1(default)

sum(b=2)(1)        # returns 3: prebind b=2, invoke with a=1.
sum(b=2)()         # wrong: `a` is not provided.

sum(1)(2)                      # wrong: 'a' is provided multiple times.
sum(1)(2, override_args=True)   # ok: override `a` value with 2.

sum()(1, 2, 3, 4)  # returns 10: a=1, b=2, *args=[3, 4]
sum(c=4)(1, 2, 3)  # returns 10: a=1, b=2, *args=[3], **kwargs={'c': 4}

Or created by subclassing pg.Functor:

class Sum(pg.Functor):
  a: int
  b: int = 1

  def _call(self) -> int:
    return self.a + self.b

Usage on subclassed functors is the same as functors created from functions.

Attributes:

bound_args	Returns bound argument names.
default_args	Returns the names of bound argument whose values are the default.
is_fully_bound	Returns if all arguments of functor is bound.
is_subclassed_functor
non_default_args	Returns the names of bound arguments whose values are not the default.
specified_args	Returns user specified argument names.
unbound_args	Returns unbound argument names.

property bound_args: Set[str]

Returns bound argument names.

property default_args: Set[str]

Returns the names of bound argument whose values are the default.

property is_fully_bound: bool

Returns if all arguments of functor is bound.

class property is_subclassed_functor: bool

Returns True if this class is a subclassed Functor.

property non_default_args: Set[str]

Returns the names of bound arguments whose values are not the default.

property specified_args: Set[str]

Returns user specified argument names.

property unbound_args: Set[str]

Returns unbound argument names.