some new features

.venv/lib/python3.12/site-packages/sklearn/utils/_available_if.py

@@ -0,0 +1,93 @@
+from functools import update_wrapper, wraps
+from types import MethodType
+
+
+class _AvailableIfDescriptor:
+    """Implements a conditional property using the descriptor protocol.
+
+    Using this class to create a decorator will raise an ``AttributeError``
+    if check(self) returns a falsey value. Note that if check raises an error
+    this will also result in hasattr returning false.
+
+    See https://docs.python.org/3/howto/descriptor.html for an explanation of
+    descriptors.
+    """
+
+    def __init__(self, fn, check, attribute_name):
+        self.fn = fn
+        self.check = check
+        self.attribute_name = attribute_name
+
+        # update the docstring of the descriptor
+        update_wrapper(self, fn)
+
+    def _check(self, obj, owner):
+        attr_err_msg = (
+            f"This {repr(owner.__name__)} has no attribute {repr(self.attribute_name)}"
+        )
+        try:
+            check_result = self.check(obj)
+        except Exception as e:
+            raise AttributeError(attr_err_msg) from e
+
+        if not check_result:
+            raise AttributeError(attr_err_msg)
+
+    def __get__(self, obj, owner=None):
+        if obj is not None:
+            # delegate only on instances, not the classes.
+            # this is to allow access to the docstrings.
+            self._check(obj, owner=owner)
+            out = MethodType(self.fn, obj)
+
+        else:
+            # This makes it possible to use the decorated method as an unbound method,
+            # for instance when monkeypatching.
+            @wraps(self.fn)
+            def out(*args, **kwargs):
+                self._check(args[0], owner=owner)
+                return self.fn(*args, **kwargs)
+
+        return out
+
+
+def available_if(check):
+    """An attribute that is available only if check returns a truthy value.
+
+    Parameters
+    ----------
+    check : callable
+        When passed the object with the decorated method, this should return
+        a truthy value if the attribute is available, and either return False
+        or raise an AttributeError if not available.
+
+    Returns
+    -------
+    callable
+        Callable makes the decorated method available if `check` returns
+        a truthy value, otherwise the decorated method is unavailable.
+
+    Examples
+    --------
+    >>> from sklearn.utils.metaestimators import available_if
+    >>> class HelloIfEven:
+    ...    def __init__(self, x):
+    ...        self.x = x
+    ...
+    ...    def _x_is_even(self):
+    ...        return self.x % 2 == 0
+    ...
+    ...    @available_if(_x_is_even)
+    ...    def say_hello(self):
+    ...        print("Hello")
+    ...
+    >>> obj = HelloIfEven(1)
+    >>> hasattr(obj, "say_hello")
+    False
+    >>> obj.x = 2
+    >>> hasattr(obj, "say_hello")
+    True
+    >>> obj.say_hello()
+    Hello
+    """
+    return lambda fn: _AvailableIfDescriptor(fn, check, attribute_name=fn.__name__)