`tempestweb.transpile`¶

The Mode C compiler: it reads the typed-Python app layer and emits native JavaScript. TranspileError carries file:line when the code leaves the supported subset — the error you will meet before any other when porting an app to a static bundle.

Guide with examples: Mode C — transpile.

tempestweb.transpile ¶

Mode C transpiler — typed Python app layer → native JavaScript.

Transcribes a tempestweb app module (state dataclasses + view + handlers) into an ES module that runs on the native JS runtime (client/transpile/runtime.js), with zero Python at execution time. See docs/modo-c-transpile.md.

TranspileError ¶

Bases: Exception

A Python construct fell outside the transpilable subset.

Carries the source location so the message reads like a compiler diagnostic (file:line: <what> is not supported), in the spirit of mypy --strict.

Source code in tempestweb/transpile/errors.py

class TranspileError(Exception):
    """A Python construct fell outside the transpilable subset.

    Carries the source location so the message reads like a compiler diagnostic
    (``file:line: <what> is not supported``), in the spirit of ``mypy --strict``.
    """

    def __init__(
        self, message: str, node: ast.AST | None, filename: str = "<source>"
    ) -> None:
        """Initialize the error.

        Args:
            message: What is unsupported and, ideally, why.
            node: The offending AST node (its ``lineno`` locates the
                diagnostic), or ``None`` when the diagnostic is about the module
                as a whole and no node carries the blame — the line then reads
                ``0``, which is still better than losing the message.
            filename: The source file name, for the ``file:line`` prefix.
        """
        line: int = getattr(node, "lineno", 0)
        self.filename: str = filename
        self.lineno: int = line
        super().__init__(f"{filename}:{line}: {message}")

transpile_source ¶

transpile_source(source: str, filename: str = '<source>', *, banner: str | None = None) -> str

Transpile Python module source into native-JS module source.

Parameters:

Name	Type	Description	Default
`source`	`str`	The Python source to transpile.	required
`filename`	`str`	Source name for diagnostics and the default banner.	`'<source>'`
`banner`	`str \| None`	Optional leading comment line (see :func:`generate`).	`None`

Returns:

Type	Description
`str`	The generated JavaScript module source.

Raises:

Type	Description
`TranspileError`	If the module uses a construct outside the subset.

Source code in tempestweb/transpile/__init__.py

def transpile_source(
    source: str, filename: str = "<source>", *, banner: str | None = None
) -> str:
    """Transpile Python module source into native-JS module source.

    Args:
        source: The Python source to transpile.
        filename: Source name for diagnostics and the default banner.
        banner: Optional leading comment line (see :func:`generate`).

    Returns:
        The generated JavaScript module source.

    Raises:
        TranspileError: If the module uses a construct outside the subset.
    """
    return generate(source, filename, banner=banner)

transpile_file ¶

transpile_file(path: str | Path, *, banner: str | None = None) -> str

Transpile a Python source file into native-JS module source.

Parameters:

Name	Type	Description	Default
`path`	`str \| Path`	Path to the `.py` module to transpile.	required
`banner`	`str \| None`	Optional leading comment line (see :func:`generate`).	`None`

Returns:

Type	Description
`str`	The generated JavaScript module source.

Raises:

Type	Description
`TranspileError`	If the module uses a construct outside the subset.

Source code in tempestweb/transpile/__init__.py

def transpile_file(path: str | Path, *, banner: str | None = None) -> str:
    """Transpile a Python source file into native-JS module source.

    Args:
        path: Path to the `.py` module to transpile.
        banner: Optional leading comment line (see :func:`generate`).

    Returns:
        The generated JavaScript module source.

    Raises:
        TranspileError: If the module uses a construct outside the subset.
    """
    file_path = Path(path)
    source = file_path.read_text(encoding="utf-8")
    return generate(source, file_path.name, banner=banner)

tempestweb.transpile¶