is_module_invalid

FunctionPrivateSource

flag: bool = is_module_invalid(module: ModuleType)

Check whether a lazy module is invalid.

This function is designed for a specific reason. Because a lazy-loaded module is not loaded instantly, it may be possible that a lazy-loaded module is not installed. This function is mainly designed for verifying this case.

Arguments

Requires

Argument	Type	Required	Description
module	ModuleType		Can be a lazy module, a module or a module placeholder.

Returns

Argument	Type	Description
flag	bool	True only when the given module is a module placeholder.

Example

Load an optional module and verify that the module is not loaded

Codes

Suppose that numpy is not installed.

verify_a_module_placeholder.py

from typing import TYPE_CHECKING
from syncstream import utils

if TYPE_CHECKING:
    import curses
else:
    curses = utils.lazy_import(
        "curses", package=None, dependencies=("numpy",), required=False
    )


print(curses)
print(utils.is_module_invalid(curses))
print(curses)

Results

<ModulePlaceholder curses>
True
<ModulePlaceholder curses>