sphinx documentation; adjusted all docstrings; moved some modules to non-public subpackage

src/asyncio_taskpool/internals/helpers.py

@@ -0,0 +1,139 @@
+__author__ = "Daniil Fajnberg"
+__copyright__ = "Copyright © 2022 Daniil Fajnberg"
+__license__ = """GNU LGPLv3.0
+
+This file is part of asyncio-taskpool.
+
+asyncio-taskpool is free software: you can redistribute it and/or modify it under the terms of
+version 3.0 of the GNU Lesser General Public License as published by the Free Software Foundation.
+
+asyncio-taskpool is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
+See the GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along with asyncio-taskpool. 
+If not, see <https://www.gnu.org/licenses/>."""
+
+__doc__ = """
+Miscellaneous helper functions. None of these should be considered part of the public API.
+"""
+
+
+from asyncio.coroutines import iscoroutinefunction
+from asyncio.queues import Queue
+from importlib import import_module
+from inspect import getdoc
+from typing import Any, Optional, Union
+
+from .types import T, AnyCallableT, ArgsT, KwArgsT
+
+
+async def execute_optional(function: AnyCallableT, args: ArgsT = (), kwargs: KwArgsT = None) -> Optional[T]:
+    """
+    Runs `function` with `args` and `kwargs` and returns its output.
+
+    Args:
+        function:
+            Any callable that accepts the provided positional and keyword-arguments.
+            If it is a coroutine function, it will be awaited.
+            If it is not a callable, nothing is returned.
+        *args (optional):
+            Positional arguments to pass to `function`.
+        **kwargs (optional):
+            Keyword-arguments to pass to `function`.
+
+    Returns:
+        Whatever `function` returns (possibly after being awaited) or `None` if `function` is not callable.
+    """
+    if not callable(function):
+        return
+    if kwargs is None:
+        kwargs = {}
+    if iscoroutinefunction(function):
+        return await function(*args, **kwargs)
+    return function(*args, **kwargs)
+
+
+def star_function(function: AnyCallableT, arg: Any, arg_stars: int = 0) -> T:
+    """
+    Calls `function` passing `arg` to it, optionally unpacking it first.
+
+    Args:
+        function:
+            Any callable that accepts the provided argument(s).
+        arg:
+            The single positional argument that `function` expects; in this case `arg_stars` should be 0.
+            Or the iterable of positional arguments that `function` expects; in this case `arg_stars` should be 1.
+            Or the mapping of keyword-arguments that `function` expects; in this case `arg_stars` should be 2.
+        arg_stars (optional):
+            Determines if and how to unpack `arg`.
+            0 means no unpacking, i.e. `arg` is passed into `function` directly as `function(arg)`.
+            1 means unpacking to an arbitrary number of positional arguments, i.e. as `function(*arg)`.
+            2 means unpacking to an arbitrary number of keyword-arguments, i.e. as `function(**arg)`.
+
+    Returns:
+        Whatever `function` returns.
+
+    Raises:
+        `ValueError`: `arg_stars` is something other than 0, 1, or 2.
+    """
+    if arg_stars == 0:
+        return function(arg)
+    if arg_stars == 1:
+        return function(*arg)
+    if arg_stars == 2:
+        return function(**arg)
+    raise ValueError(f"Invalid argument arg_stars={arg_stars}; must be 0, 1, or 2.")
+
+
+async def join_queue(q: Queue) -> None:
+    """Wrapper function around the join method of an `asyncio.Queue` instance."""
+    await q.join()
+
+
+def get_first_doc_line(obj: object) -> str:
+    """Takes an object and returns the first (non-empty) line of its docstring."""
+    return getdoc(obj).strip().split("\n", 1)[0].strip()
+
+
+async def return_or_exception(_function_to_execute: AnyCallableT, *args, **kwargs) -> Union[T, Exception]:
+    """
+    Returns the output of a function or the exception thrown during its execution.
+
+    Args:
+        _function_to_execute:
+            Any callable that accepts the provided positional and keyword-arguments.
+        *args (optional):
+            Positional arguments to pass to `_function_to_execute`.
+        **kwargs (optional):
+            Keyword-arguments to pass to `_function_to_execute`.
+
+    Returns:
+        Whatever `_function_to_execute` returns or throws. (An exception is not raised, but returned!)
+    """
+    try:
+        if iscoroutinefunction(_function_to_execute):
+            return await _function_to_execute(*args, **kwargs)
+        else:
+            return _function_to_execute(*args, **kwargs)
+    except Exception as e:
+        return e
+
+
+def resolve_dotted_path(dotted_path: str) -> object:
+    """
+    Resolves a dotted path to a global object and returns that object.
+
+    Algorithm shamelessly stolen from the `logging.config` module from the standard library.
+    """
+    names = dotted_path.split('.')
+    module_name = names.pop(0)
+    found = import_module(module_name)
+    for name in names:
+        try:
+            found = getattr(found, name)
+        except AttributeError:
+            module_name += f'.{name}'
+            import_module(module_name)
+            found = getattr(found, name)
+    return found