docs/library/enum.rst: Add Enum class.

IhorNehrutsa · IhorNehrutsa · commit a6ec2fad74ba · 2025-03-05T09:42:06.000+02:00
Signed-off-by: Ihor Nehrutsa &lt;Ihor.Nehrutsa@gmail.com&gt;
diff --git a/docs/library/enum.rst b/docs/library/enum.rst
@@ -0,0 +1,188 @@
+:mod:`enum` -- MicroPython Enum class like in the Python
+========================================================
+
+.. module:: enum
+   :synopsis: MicroPython Enum class like in the Python
+
+This module implements enumeration Enum class for the MicroPython.
+
+class Enum -- enumeration
+-------------------------
+
+Class Enum is based in dictionary `dict` class and provides a way to create enumeration
+objects with key-value pairs.
+
+Constructor
+-----------
+
+.. class:: Enum(arg)
+
+   Construct and return a new Enum object using the following parameter:
+
+      - *arg* is the dictionary of key-value pairs.
+
+Usage example::
+
+    from enum import Enum
+    e = Enum({"X": 1, "Y": 2})                          # create Enum object from dictionary of key-value pairs
+    print(e)
+    print("add new key-value pair")
+    e.A = 'A'                                           # add new key-value pair
+    e.B = 'B'
+    print(e)
+    print("e.X:", e.X)                                  # get value from key
+    print("e.X.value:", e.X.value)                      # get value from key
+    print("e(e.X):", e(e.X))                            # get value from key
+    print("e.key_from_value(1):", e.key_from_value(1))  # get key from value
+    print("e.is_value(e.B):", e.is_value(e.B))
+    print("del e.B")
+    del e.B                                             # delete key-value pair
+    print(e)
+    print("e.is_value('B'):", e.is_value('B'))          # check if the value is in the Enum object
+    print("e.B: will raise the KeyError exception")
+    print(e.B)                                          # raise an exception due to no such a key attribute
+
+Output is::
+
+    Enum({'Y': 2, 'X': 1})
+    add new key-value pair
+    Enum({'A': 'A', 'B': 'B', 'Y': 2, 'X': 1})
+    e.X: 1
+    e.X.value: 1
+    e(e.X): 1
+    e.key_from_value(1): Enum.X
+    e.is_value(e.B): True
+    del e.B
+    Enum({'A': 'A', 'Y': 2, 'X': 1})
+    e.is_value('B'): False
+    e.B: will raise the KeyError exception
+    Traceback (most recent call last):
+    File "<stdin>", line 234, in <module>
+    File "<stdin>", line 126, in __getattr__
+    KeyError: no such attribute: B
+
+Methods
+-------
+
+.. _Enum_append:
+.. method:: Enum.append(arg, **kw_args):
+
+    Append key-value pairs with the following parameters:
+
+      - *arg* is the dictionary of key-value pairs.
+      - *kw_args* are key1=value1, key2=value2, ...
+
+.. method:: Enum.is_value(value)
+
+    Check if the value is in the Enum object.
+    Returns True if the value is in the Enum object, and False otherwise.
+
+.. method:: Enum.key_from_value(value)
+
+    Returns the key from the value. If a value is not in the Enum object, it raises an exception.
+
+Usage example::
+
+    from enum import Enum
+
+    class State(Enum):
+        Stop = 10
+        Run = 20
+        Ready = 30
+
+    state = State()
+    print("state:", State())
+
+    current_state = state.Stop
+    print("current_state:", current_state, state.key_from_value(current_state))
+    if current_state == state.Stop:
+        print(" Stop state")
+    if current_state != state.Ready:
+        print(" Not a Ready state")
+        print(" Run!")
+        current_state = state.Run
+    print("current_state:", current_state, state.key_from_value(current_state))
+    # some process
+    i = -1
+    while current_state != state.Ready:
+        i += 1
+        if state.is_value(i):
+            if state(i) == state.Ready:
+                current_state = state.Ready
+        print(".", end="")
+    print()
+    print("current_state:", current_state, state.key_from_value(current_state))
+    print("Done!")
+
+Output is::
+
+    state: State({'Ready': 30, 'Stop': 10, 'Run': 20})
+    current_state: 10 State.Stop
+    Stop state
+    Not a Ready state
+    Run!
+    current_state: 20 State.Run
+    ...............................
+    current_state: 30 State.Ready
+    Done!
+
+.. warning::
+
+    There is the trouble with the isinstance()/type().
+
+    >>> isinstance(State.Run, State)
+    False
+    >>> State(State.Ready) == State.Ready
+    False
+    >>> int(str(State(State.Ready))) == State.Ready
+    True
+    >>> type(State(State.Ready))
+    <class 'State'>
+    >>> type(state(State.Ready))
+    <class 'int'>
+    >>> state(State.Ready) == State.Ready
+    True
+
+Function
+--------
+
+.. function:: enum(**kw_args)
+
+    Returns an Enum object from the following parameters:
+
+      - *kw_args* are key1=value1, key2=value2, ...
+
+Usage examples::
+
+    from enum import enum
+    e = enum()
+    repr(e)
+    str(e)
+    e = enum(X=1, Y=2.0, A='A', ON=True)
+    repr(e)
+    str(e)
+    e.X
+    e.Y
+    e.A
+    e.ON
+
+Output::
+
+    '{}'
+    'Enum({})'
+    "{'A': 'A', 'ON': True, 'Y': 2.0, 'X': 1}"
+    "Enum({'A': 'A', 'ON': True, 'Y': 2.0, 'X': 1})"
+    1
+    2.0
+    'A'
+    True
+
+.. note::
+
+    ZZZ.
+
+.. seealso::
+
+..
+    :ref:`enum_test.py <enum_test.py>`
+    :ref:`enum.py <enum.py>`
diff --git a/docs/library/index.rst b/docs/library/index.rst
@@ -62,6 +62,7 @@ library.
    builtins.rst
    cmath.rst
    collections.rst
+   enum.rst
    errno.rst
    gc.rst
    gzip.rst
