This rule raises an issue when a `TypeVar` is used in a function instead of the generic function type syntax.

== Why is this an issue?

Prior to Python 3.12 functions using generic types were created as follows:

[source,python]
----
from typing import TypeVar

_T = TypeVar("_T")

def func(a: _T, b: _T) -> _T:
    ...
----

This snippet of code can be confusing and difficult to read. This is why is it a good idea to 
use the new type parameter syntax of Python 3.12 that allows for a more concise and more readable code by removing the 
`TypeVar` and its import statement:

[source,python]
----
def func[T](a: T, b: T) -> T:
    ...
----

=== Exceptions

This rule will only raise an issue when the Python version of the analyzed project is set to 3.12 or higher.

== How to fix it

To fix this issue, replace the usage of a `TypeVar` as a parameter type with the generic type parameter syntax.

=== Code examples

==== Noncompliant code example

[source,python,diff-id=1,diff-type=noncompliant]
----
from typing import TypeVar

_T = TypeVar("_T", bound=str)

def func(a: _T, b: int) -> _T: # Noncompliant: the usage of a TypeVar could be simplified with a generic type parameter.
    ...
----

==== Compliant solution

[source,python,diff-id=1,diff-type=compliant]
----
def func[T: str](a: T, b: int) -> T: # Compliant: the code is clear and concise.
    ...
----


== Resources
=== Documentation

* Python Documentation - https://docs.python.org/3.12/reference/simple_stmts.html#type[The type statement]
* Python 3.12 Release Notes - https://docs.python.org/3.12/whatsnew/3.12.html#pep-695-type-parameter-syntax[PEP 695: Type Parameter Syntax]
* PEP 695 - https://peps.python.org/pep-0695/[Type Parameter Syntax]

ifdef::env-github,rspecator-view[]

'''

== Implementation Specification
=== Message
(visible only on this page)

Use a generic type parameter for this function instead of a `TypeVar`.

'''
endif::env-github,rspecator-view[]