fqr.cli.lib module

CLI imports.

class TypeVarTuple

Bases: object

Type variable tuple. A specialized form of type variable that enables variadic generics.

The preferred way to construct a type variable tuple is via the dedicated syntax for generic functions, classes, and type aliases, where a single ‘*’ indicates a type variable tuple:

.. code::

def move_first_element_to_last[T, *Ts](tup: tuple[T, *Ts]) -> tuple[*Ts, T]:

return (*tup[1:], tup[0])

For compatibility with Python 3.11 and earlier, TypeVarTuple objects can also be created as follows:

.. code::

Ts = TypeVarTuple(‘Ts’) # Can be given any name

Just as a TypeVar (type variable) is a placeholder for a single type, a TypeVarTuple is a placeholder for an arbitrary number of types. For example, if we define a generic class using a TypeVarTuple:

.. code::

class C[*Ts]: …

Then we can parameterize that class with an arbitrary number of type arguments:

.. code::

C[int] # Fine C[int, str] # Also fine C[()] # Even this is fine

For more details, see PEP 646.

Note that only TypeVarTuples defined in the global scope can be pickled.