updade from Atlas repo

25-class-metaprog/hours/hours.py

@@ -0,0 +1,115 @@
+"""
+Abusing ``__class_getitem__`` to make a nano-DSL for working
+with hours, minutes, and seconds--these last two in base 60.
+
+``H`` is an alias for the ``Hours`` class::
+
+    >>> H[1]
+    1:00
+    >>> H[1:30]
+    1:30
+    >>> H[1::5]
+    1:00:05
+    >>> H[::5]
+    0:00:05
+
+An ``H`` instance can be converted to a float number of hours::
+
+    >>> float(H[1:15])
+    1.25
+    >>> float(H[1:30:30])  # doctest: +ELLIPSIS
+    1.5083333...
+    >>> float(H[1::5])     # doctest: +ELLIPSIS
+    1.0013888...
+
+The ``H`` constructor accepts hours, minutes, and/or seconds::
+
+    >>> H(1.5)
+    1:30
+    >>> H(1.9)
+    1:54
+    >>> H(1, 30, 30)
+    1:30:30
+    >>> H(s = 7205)
+    2:00:05
+    >>> H(1/3)
+    0:20
+    >>> H(1/1000)
+    0:00:03.6
+
+An ``H`` instance is iterable, for convenient unpacking::
+
+    >>> hms = H[1:22:33]
+    >>> h, m, s = hms
+    >>> h, m, s
+    (1, 22, 33)
+    >>> tuple(hms)
+    (1, 22, 33)
+
+
+``H`` instances can be added::
+
+    >>> H[1:45:12] + H[2:15:50]
+    4:01:02
+"""
+
+from typing import Tuple, Union
+
+
+def normalize(s: float) -> Tuple[int, int, float]:
+    h, r = divmod(s, 3600)
+    m, s = divmod(r, 60)
+    return int(h), int(m), s
+
+
+def valid_base_60(n, unit):
+    if not (0 <= n < 60):
+        raise ValueError(f'invalid {unit} {n}')
+    return n
+
+
+class Hours:
+    h: int
+    _m: int
+    _s: float
+
+    def __class_getitem__(cls, parts: Union[slice, float]) -> 'Hours':
+        if isinstance(parts, slice):
+            h = parts.start or 0
+            m = valid_base_60(parts.stop or 0, 'minutes')
+            s = valid_base_60(parts.step or 0, 'seconds')
+        else:
+            h, m, s = normalize(parts * 3600)
+        return Hours(h, m, s)
+
+    def __init__(self, h: float = 0, m: float = 0, s: float = 0):
+        if h < 0 or m < 0 or s < 0:
+            raise ValueError('invalid negative argument')
+        self.h, self.m, self.s = normalize(h * 3600 + m * 60 + s)
+
+    def __repr__(self):
+        h, m, s = self
+        display_s = f'{s:06.3f}'
+        display_s = display_s.rstrip('0').rstrip('.')
+        if display_s == '00':
+            return f'{h}:{m:02d}'
+        return f'{h}:{m:02d}:{display_s}'
+
+    def __float__(self):
+        return self.h + self.m / 60 + self.s / 3600
+
+    def __eq__(self, other):
+        return repr(self) == repr(other)
+
+    def __iter__(self):
+        yield self.h
+        yield self.m
+        yield self.s
+
+    def __add__(self, other):
+        if not isinstance(other, Hours):
+            return NotImplemented
+        return Hours(*(a + b for a, b in zip(self, other)))
+
+
+H = Hours