knit_script.knit_script_interpreter.statements.try_catch_statements module

Try catch execution.

This module provides the Try_Catch_Statement class, which implements exception handling control flow in knit script programs. It allows programs to gracefully handle errors and exceptions that may occur during knitting operations, providing robust error recovery mechanisms.

class Try_Catch_Statement(parser_node, try_statement, catch_statement, errors)

Bases: Statement

Manages try-catch exception handling structure.

Executes a statement within a try block, and if specified exceptions occur, executes a catch block. Supports filtering by specific exception types and binding caught exceptions to variables for inspection and handling.

This statement provides robust error handling capabilities for knit script programs, allowing developers to anticipate and handle potential issues like machine configuration errors, invalid operations, or resource constraints. The try-catch mechanism ensures that programs can recover gracefully from errors rather than terminating unexpectedly.

_try_statement

The statement to execute within the try block.

Type:

Statement

_catch_statement

The statement to execute if an exception occurs.

Type:

Statement

_errors

List of expressions that evaluate to exception types to catch.

Type:

list[Expression]

__init__(parser_node, try_statement, catch_statement, errors)

Initialize a try-catch statement.

Parameters:

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

• try_statement (Statement) – The statement to execute within the try block.

• catch_statement (Statement) – The statement to execute if a matching exception occurs.

• errors (list[Expression]) – List of expressions that evaluate to exception types to catch.

• empty (Can include Assignment expressions to bind the exception to a variable. If)

• exceptions. (catches all)

execute(context)

Execute the try-catch block using Python’s exception handling.

Attempts to execute the try statement. If an exception occurs and matches one of the specified error types (or if no types are specified), executes the catch statement. If the error expression is an Assignment, binds the exception to the specified variable name in a new scope.

Parameters:

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

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