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| -rw-r--r-- | Doc/library/typing.rst | 97 |
1 files changed, 50 insertions, 47 deletions
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index 594933c..e09b647 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -20,8 +20,9 @@ The function below takes and returns a string and is annotated as follows:: def greeting(name: str) -> str: return 'Hello ' + name -In the function `greeting`, the argument `name` is expected to by of type `str` -and the return type `str`. Subtypes are accepted as arguments. +In the function ``greeting``, the argument ``name`` is expected to by of type +:class:`str` and the return type :class:`str`. Subtypes are accepted as +arguments. Type aliases ------------ @@ -49,8 +50,8 @@ For example:: It is possible to declare the return type of a callable without specifying the call signature by substituting a literal ellipsis -for the list of arguments in the type hint: `Callable[..., ReturnType]`. -`None` as a type hint is a special case and is replaced by `type(None)`. +for the list of arguments in the type hint: ``Callable[..., ReturnType]``. +``None`` as a type hint is a special case and is replaced by ``type(None)``. Generics -------- @@ -108,11 +109,12 @@ A user-defined class can be defined as a generic class. def log(self, message: str) -> None: self.logger.info('{}: {}'.format(self.name, message)) -`Generic[T]` as a base class defines that the class `LoggedVar` takes a single -type parameter `T` . This also makes `T` valid as a type within the class body. +``Generic[T]`` as a base class defines that the class ``LoggedVar`` takes a +single type parameter ``T`` . This also makes ``T`` valid as a type within the +class body. -The `Generic` base class uses a metaclass that defines `__getitem__` so that -`LoggedVar[t]` is valid as a type:: +The :class:`Generic` base class uses a metaclass that defines +:meth:`__getitem__` so that ``LoggedVar[t]`` is valid as a type:: from typing import Iterable @@ -132,7 +134,7 @@ be constrained:: class StrangePair(Generic[T, S]): ... -Each type variable argument to `Generic` must be distinct. +Each type variable argument to :class:`Generic` must be distinct. This is thus invalid:: from typing import TypeVar, Generic @@ -152,9 +154,9 @@ You can use multiple inheritance with `Generic`:: class LinkedList(Sized, Generic[T]): ... -Subclassing a generic class without specifying type parameters assumes `Any` -for each position. In the following example, `MyIterable` is not generic but -implicitly inherits from `Iterable[Any]`:: +Subclassing a generic class without specifying type parameters assumes +:class:`Any` for each position. In the following example, ``MyIterable`` is +not generic but implicitly inherits from ``Iterable[Any]``:: from typing import Iterable @@ -162,24 +164,24 @@ implicitly inherits from `Iterable[Any]`:: Generic metaclasses are not supported. -The `Any` type --------------- +The :class:`Any` type +--------------------- -A special kind of type is `Any`. Every type is a subtype of `Any`. -This is also true for the builtin type object. However, to the static type -checker these are completely different. +A special kind of type is :class:`Any`. Every type is a subtype of +:class:`Any`. This is also true for the builtin type object. However, to the +static type checker these are completely different. -When the type of a value is `object`, the type checker will reject almost all -operations on it, and assigning it to a variable (or using it as a return value) -of a more specialized type is a type error. On the other hand, when a value has -type `Any`, the type checker will allow all operations on it, and a value of -type `Any` can be assigned to a variable (or used as a return value) of a more -constrained type. +When the type of a value is :class:`object`, the type checker will reject +almost all operations on it, and assigning it to a variable (or using it as a +return value) of a more specialized type is a type error. On the other hand, +when a value has type :class:`Any`, the type checker will allow all operations +on it, and a value of type :class:`Any` can be assigned to a variable (or used +as a return value) of a more constrained type. Default argument values ----------------------- -Use a literal ellipsis `...` to declare an argument as having a default value:: +Use a literal ellipsis ``...`` to declare an argument as having a default value:: from typing import AnyStr @@ -195,9 +197,10 @@ The module defines the following classes, functions and decorators: Special type indicating an unconstrained type. - * Any object is an instance of `Any`. - * Any class is a subclass of `Any`. - * As a special case, `Any` and `object` are subclasses of each other. + * Any object is an instance of :class:`Any`. + * Any class is a subclass of :class:`Any`. + * As a special case, :class:`Any` and :class:`object` are subclasses of + each other. .. class:: TypeVar @@ -224,22 +227,22 @@ The module defines the following classes, functions and decorators: return x if len(x) >= len(y) else y The latter example's signature is essentially the overloading - of `(str, str) -> str` and `(bytes, bytes) -> bytes`. Also note - that if the arguments are instances of some subclass of `str`, - the return type is still plain `str`. + of ``(str, str) -> str`` and ``(bytes, bytes) -> bytes``. Also note + that if the arguments are instances of some subclass of :class:`str`, + the return type is still plain :class:`str`. - At runtime, `isinstance(x, T)` will raise `TypeError`. In general, - `isinstance` and `issublass` should not be used with types. + At runtime, ``isinstance(x, T)`` will raise :exc:`TypeError`. In general, + :func:`isinstance` and :func:`issublass` should not be used with types. Type variables may be marked covariant or contravariant by passing - `covariant=True` or `contravariant=True`. See :pep:`484` for more + ``covariant=True`` or ``contravariant=True``. See :pep:`484` for more details. By default type variables are invariant. .. class:: Union - Union type; `Union[X, Y]` means either X or Y. + Union type; ``Union[X, Y]`` means either X or Y. - To define a union, use e.g. `Union[int, str]`. Details: + To define a union, use e.g. ``Union[int, str]``. Details: * The arguments must be types and there must be at least one. @@ -259,37 +262,37 @@ The module defines the following classes, functions and decorators: Union[int, str] == Union[str, int] - * If `Any` is present it is the sole survivor, e.g.:: + * If :class:`Any` is present it is the sole survivor, e.g.:: Union[int, Any] == Any * You cannot subclass or instantiate a union. - * You cannot write `Union[X][Y]` + * You cannot write ``Union[X][Y]`` - * You can use `Optional[X]` as a shorthand for `Union[X, None]`. + * You can use ``Optional[X]`` as a shorthand for ``Union[X, None]``. .. class:: Optional Optional type. - `Optional[X]` is equivalent to `Union[X, type(None)]`. + ``Optional[X]`` is equivalent to ``Union[X, type(None)]``. .. class:: Tuple - Tuple type; `Tuple[X, Y]` is the is the type of a tuple of two items + Tuple type; ``Tuple[X, Y]`` is the is the type of a tuple of two items with the first item of type X and the second of type Y. - Example: `Tuple[T1, T2]` is a tuple of two elements corresponding - to type variables T1 and T2. `Tuple[int, float, str]` is a tuple + Example: ``Tuple[T1, T2]`` is a tuple of two elements corresponding + to type variables T1 and T2. ``Tuple[int, float, str]`` is a tuple of an int, a float and a string. To specify a variable-length tuple of homogeneous type, - use literal ellipsis, e.g. `Tuple[int, ...]`. + use literal ellipsis, e.g. ``Tuple[int, ...]``. .. class:: Callable - Callable type; `Callable[[int], str]` is a function of (int) -> str. + Callable type; ``Callable[[int], str]`` is a function of (int) -> str. The subscription syntax must always be used with exactly two values: the argument list and the return type. The argument list @@ -297,9 +300,9 @@ The module defines the following classes, functions and decorators: There is no syntax to indicate optional or keyword arguments, such function types are rarely used as callback types. - `Callable[..., ReturnType]` could be used to type hint a callable - taking any number of arguments and returning `ReturnType`. - A plain `Callable` is equivalent to `Callable[..., Any]`. + ``Callable[..., ReturnType]`` could be used to type hint a callable + taking any number of arguments and returning ``ReturnType``. + A plain :class:`Callable` is equivalent to ``Callable[..., Any]``. .. class:: Generic |