Module mpython.utils

Classes

class DelayedImport

Expand source code

class DelayedImport:
    """A utility to delay the import of modules or variables.

    Until they are imported, import paths are wrapped in a
    `DelayedImportElement` object. The first time an element is accessed,
    it triggers the underlying import and assign the imported module or
    object into the `DelayedImport` child class, while getting rid
    of the `DelayedImportElement` wrapper. Thereby, the next time the
    element is accessed, the module is directly obtained. This strategy
    minimizes overhead on subsequent calls (no need to test whether
    the module has already been imported or not).

    Example
    -------
    ```python
    # module_with_definitions.py
    class _imports(DelayedImport):
        Array = 'mpython.array.Array'
        Cell = 'mpython.cell.Cell'

    def foo():
        Array = _imports.Array
        Cell = _imports.Cell
    ```
    """
    def __init_subclass__(cls):
        for key, val in cls.__dict__.items():
            if key.startswith("__"):
                continue
            setattr(cls, key, DelayedImportElement(key, val))

A utility to delay the import of modules or variables.

Until they are imported, import paths are wrapped in a DelayedImportElement object. The first time an element is accessed, it triggers the underlying import and assign the imported module or object into the DelayedImport child class, while getting rid of the DelayedImportElement wrapper. Thereby, the next time the element is accessed, the module is directly obtained. This strategy minimizes overhead on subsequent calls (no need to test whether the module has already been imported or not).

Example

# module_with_definitions.py
class _imports(DelayedImport):
    Array = 'mpython.array.Array'
    Cell = 'mpython.cell.Cell'

def foo():
    Array = _imports.Array
    Cell = _imports.Cell

Subclasses

• mpython.array._imports
• mpython.core.base_types._imports
• mpython.core.delayed_types._imports
• mpython.core.mixin_types._imports
• mpython.core.wrapped_types._imports
• mpython.struct._imports

class DelayedImportElement (name, import_path=None)

Expand source code

def __get__(self, instance, owner):
    assert instance is None
    imported = self._import()
    setattr(owner, self.name, imported)
    return imported