knit_script.knit_script_interpreter.statements.xfer_pass_statement module

Statement for executing a transfer pass.

This module provides the Xfer_Pass_Statement class, which handles transfer operations between needle beds and to slider needles. It manages the complex racking requirements and bed-specific processing needed for reliable stitch transfers.

class Xfer_Pass_Statement(parser_node, racking, needles, bed, is_sliders=False)

Bases: Statement

Executes transfer operations at specified racking with target needles.

This statement manages the transfer of stitches between needle beds or to sliders,

handling the complex racking requirements for different bed configurations and ensuring proper sequencing of operations. For non-zero racking, it separates front and back bed transfers since they require different racking values due to the mechanical constraints of the knitting machine.

The transfer pass handles evaluation of needle expressions, racking calculations, bed filtering, and creation of appropriate carriage pass specifications for reliable stitch transfer operations.

_is_sliders

True if transferring to sliders instead of regular needles.

Type:

bool

_bed

Expression that evaluates to the target bed position.

Type:

Expression | None

_racking

Expression that evaluates to the racking position for transfers.

Type:

Expression

_needles

List of expressions that evaluate to needles to transfer from.

Type:

list[Expression]

__init__(parser_node, racking, needles, bed, is_sliders=False)

Initialize a transfer pass statement.

Parameters:

• parser_node (LRStackNode) – The parser node from the abstract syntax tree.

• racking (Expression) – Expression that evaluates to the racking position for transfers.

• needles (list[Expression]) – List of expressions that evaluate to needles to transfer from.

• bed (Expression | None) – Expression that evaluates to the target bed position, or None to transfer to the opposite bed. Needles already on the target bed are excluded from the transfer.

• is_sliders (bool, optional) – True if transferring to sliders instead of regular needles. Defaults to False.

execute(context)

Execute transfer operations with proper racking and bed handling.

Evaluates all needle expressions, determines the target bed, and creates appropriate carriage pass specifications. For non-zero racking, separates front and back bed transfers since they require different racking values due to mechanical constraints.

Parameters:

context (Knit_Script_Context) – The current execution context of the knit script interpreter.

Raises:

TypeError – If needle expressions don’t evaluate to Needle objects or if the bed expression doesn’t evaluate to a Machine_Bed_Position.

classmethod __class_getitem__(params)

Parameterizes a generic class.

At least, parameterizing a generic class is the main thing this method does. For example, for some generic class Foo, this is called when we do Foo[int] - there, with cls=Foo and params=int.

However, note that this method is also called when defining generic classes in the first place with class Foo(Generic[T]): ….

classmethod __init_subclass__(**kwargs)

Automatically wrap execute methods in subclasses with appropriate error handling and debugging decorators.

This method is called whenever a class inherits from Statement. It checks if the subclass defines its own execute method and wraps it with the appropriate decorators

Parameters:

**kwargs (Any) – Additional keyword arguments passed to super().__init_subclass__

property file_name: str | None

Returns: str | None: The file name of the knitscript program this was parsed from or None if the program was passed as a string.

property line_number: int

Get the line number of the symbol that generated this statement.

Returns:

The line number where this element appears in the source file.

Return type:

int

property local_path: str | None

Returns: str | None: The path to the directory containing the file from which this element was parsed or None if the value was parsed from a python string.

property location: Location

Get the location of this symbol in KnitScript file.

Returns:

The location of this symbol in the source file, including file name, line number, and position information.

Return type:

Location

property location_str: str

Returns: str: The string referencing the line number and possible file name information about this element.

property position_context: str

The position context string is the string from the knitscript program from which this element was parsed. The context string will begin at the start of this element and continue to the end of the line of knitscript or a semicolon on new line are reached.

Returns:

The string used to contextualize this element in the knitscript program.

Return type:

str