pipeline.links

Link classes for the pipeline framework.

Contains:

LinkList: list subclass supporting the | operator to combine links
Link: connects an output port of one module to an input port of another
ConditionalLink: a Link that transfers data only when a runtime condition is True

Classes

class pipeline.links.LinkList

A list subclass that supports the | operator for chaining Link objects.

Inherits from:: list

class pipeline.links.Link

A link to link the output port of parent module and input port of child module.

Methods:

Initialize the Link object.

Parameters

parentPipeModule | PortReference: The parent module or a PortReference for the output port.
childPipeModule | PortReference: The child module or a PortReference for the input port.
port_outstr, default: None: The output port name of the parent module. When it’s None, the first output port will be used. Ignored if parent is a PortReference.
port_instr, default: None: The input port name of the child module. When it’s None, the first input port will be used. Ignored if child is a PortReference.

connect(connection: tuple) → Link

Create a Link from a tuple of PortReference objects.

Parameters

connectiontuple: A tuple of (output_port_reference, input_port_reference)

Returns

Any

Link
    The created link

Examples

>>> link = Link.connect((parent.OutputPort, child.InputPort))

chain() → list[Link]

Create multiple Links from chained connections.

Parameters

*connectionsPortReference or Link: Chain of connections using >> operator or existing Link objects

Returns

Any

list[Link]
    List of created links

Examples

>>> links = Link.chain(
...     parent.OutputPort >> child.InputPort,
...     child.OutputResult >> final.InputData
... )

when(condition: Callable[[PipeModule], bool] | str) → ConditionalLink

Convert this link into a ConditionalLink with a runtime condition.

Auto-detects the condition type from the argument:

- **Callable** → used directly as the condition function (Python-only, not
  serializable into .pipe files).
  Signature: ````condition(parent_module: PipeModule) -> bool````
- **str that is a valid Python identifier** → treated as ````condition_name````:
  the name of a function in the pipeline's ````local_functions_path```` file.
  Fully serializable.
- **str with operators / spaces** → treated as ````condition_expr````: a Python
  expression evaluated with the parent module's output port data and

Parameters

conditionCallable | str: The condition to apply. Type is auto-detected as described above.

Returns

Any: ConditionalLink

Examples

>>> # Expression string – port data available by name
>>> (scorer.OutputScore >> grader.InputData).when("OutputScore > 0.5")

>>> # Function name – resolved from pipeline.local_functions_path
>>> (scorer.OutputScore >> grader.InputData).when("check_score_valid")

>>> # Callable – convenient but not serializable
>>> (scorer.OutputScore >> grader.InputData).when(
...     lambda m: m["OutputScore"] is not None and m["OutputScore"] > 0.5
... )

class pipeline.links.ConditionalLink

A Link that only transfers data when a runtime condition evaluates to True.

When the condition evaluates to False, the link and all its downstream
descendants are skipped for that pipeline run — no data is transferred
and the child module is not executed.

Three ways to specify a condition (evaluated in priority order):

#. **condition** (Callable) — a Python callable for interactive / script use.
   Not serializable into ````.pipe```` files.
   Signature: ````condition(parent_module: PipeModule) -> bool````

#. **condition_name** (str, valid Python identifier) — the name of a function
   in the pipeline's ````local_functions_path```` file.  Fully serializable.
   The function must accept a single ````PipeModule```` argument and return ````bool````.

#. **condition_expr** (str, expression) — a Python expression evaluated with
   the parent module's output port data and attributes available as variables.
   Fully serializable.
   Port names always start with ````Input````/````Output````, so they never collide
   with attribute names in the evaluation context.

Parameters

parentPipeModule | PortReference: Source module or output PortReference.
childPipeModule | PortReference: Target module or input PortReference. port_out : str, optional Output port name on the parent (auto-selected if None). port_in : str, optional Input port name on the child (auto-selected if None). lname : str, optional Custom link name. condition : Callable[[PipeModule], bool], optional Runtime callable. Takes the parent module and returns bool. condition_name : str, optional Name of a function in ``pipeline.local_functions_path``. condition_expr : str, optional Python expression string. Parent output ports and attributes are available as variables by their names.

Examples

>>> # Fluent API (recommended)
>>> (scorer.OutputScore >> grader.InputData).when("OutputScore > 0.5")

>>> # Direct construction with expression
>>> ConditionalLink(
...     scorer.OutputScore, grader.InputData,
...     condition_expr="OutputScore > 0.5",
... )

>>> # Direct construction with function name
>>> ConditionalLink(
...     scorer.OutputScore, grader.InputData,
...     condition_name="check_score_valid",
... )

Inherits from:: Link

Methods:

__init__(parent: PipeModule | PortReference, child: PipeModule | PortReference, port_out: str | None = None, port_in: str | None = None, lname: str | None = None, condition: Callable[[PipeModule], bool] | None = None, condition_name: str | None = None, condition_expr: str | None = None) → None

evaluate(parent_module: PipeModule, local_functions_path: str | Path | None = None) → bool

Evaluate the condition against the parent module.

Condition types are tried in priority order: callable → condition_name → condition_expr. Returns ``True`` when no condition is set (acts as a regular unconditional link).

Parameters

parent_modulePipeModule: The parent module whose ports and attributes are exposed to the condition. local_functions_path : str | Path, optional Path to the local functions file; required when ``condition_name`` is set.

Returns

Any

bool
    Whether the link should transfer data and trigger child execution.