hio.base.hier.needing

hio.base.hier.needing Module

Provides hierarchical action support

Module Contents

class hio.base.hier.needing.Need(*, expr='True', hold=None, **kwa)

Bases: hio.hioing.Mixin

Need is conditional callable class whose callable returns a boolean. The calling it evaluates a need expression. May be used as the transition condition of a Gact.

Attributes:

hold (Hold): data shared by boxwork

Properties:

expr (str): evaluable boolean expression. compiled (bool): True means ._code holds compiled ._expr; False means not yet compiled

Hidden:

_expr (str): evaluable boolean expression. _code (None|CodeType): compiled evaluable boolean expression .expr; None means not yet compiled from .expr

Compilation Notes:

The need returned by an on() call keeps the string expression because compiled code objects are not pickleable. In multiprocessing, the child process recompiles the expression from the string form. Keeping the string representation also helps debugging and introspection.

Expression Syntax Notes:

H is a local reference to self.hold during evaluation. Need expressions can use dotted hold paths directly, for example, H.root_dog.value. This is equivalent to either self.hold["root_dog"].value or self.hold[("root", "dog")].value.

The expression H.root_dog.value > 5 compiles and evaluates directly as long as H is present in locals and references a Hold instance. No substitution shorthand is required. Hierarchy in .hold uses underscore-separated keys, so Box/Boxer/Actor names may not contain _ (enforced by the Renam regex).

property expr

Property getter for ._expr

Returns:

evaluable boolean expression.

Return type:

expr (str)

property compiled

Property compiled

Returns:

compiled (bool): True means ._code holds compiled ._expr
                 False means not yet compiled

compile()

Compile evaluable boolean expression str ._expr into compiled code object ._code to be evaluated at run time. Because code objects are not pickleable the compilation must happen at prep (enter) time not init time.