Add a couple of functions from jaraco.functools.

Author: jaraco

importlib_metadata/_functools.py

@@ -102,3 +102,57 @@ def wrapper(param, *args, **kwargs):
             return func(param, *args, **kwargs)
 
     return wrapper
+
+
+# From jaraco.functools 4.0.2
+def compose(*funcs):
+    """
+    Compose any number of unary functions into a single unary function.
+
+    Comparable to
+    `function composition <https://en.wikipedia.org/wiki/Function_composition>`_
+    in mathematics:
+
+    ``h = g ∘ f`` implies ``h(x) = g(f(x))``.
+
+    In Python, ``h = compose(g, f)``.
+
+    >>> import textwrap
+    >>> expected = str.strip(textwrap.dedent(compose.__doc__))
+    >>> strip_and_dedent = compose(str.strip, textwrap.dedent)
+    >>> strip_and_dedent(compose.__doc__) == expected
+    True
+
+    Compose also allows the innermost function to take arbitrary arguments.
+
+    >>> round_three = lambda x: round(x, ndigits=3)
+    >>> f = compose(round_three, int.__truediv__)
+    >>> [f(3*x, x+1) for x in range(1,10)]
+    [1.5, 2.0, 2.25, 2.4, 2.5, 2.571, 2.625, 2.667, 2.7]
+    """
+
+    def compose_two(f1, f2):
+        return lambda *args, **kwargs: f1(f2(*args, **kwargs))
+
+    return functools.reduce(compose_two, funcs)
+
+
+def apply(transform):
+    """
+    Decorate a function with a transform function that is
+    invoked on results returned from the decorated function.
+
+    >>> @apply(reversed)
+    ... def get_numbers(start):
+    ...     "doc for get_numbers"
+    ...     return range(start, start+3)
+    >>> list(get_numbers(4))
+    [6, 5, 4]
+    >>> get_numbers.__doc__
+    'doc for get_numbers'
+    """
+
+    def wrap(func):
+        return functools.wraps(func)(compose(transform, func))
+
+    return wrap