ch05: new chapter

05-record-like/typing_namedtuple/coordinates.py

@@ -0,0 +1,22 @@
+"""
+``Coordinate``: a simple ``NamedTuple`` subclass with a custom ``__str__``::
+
+    >>> moscow = Coordinate(55.756, 37.617)
+    >>> print(moscow)
+    55.8°N, 37.6°E
+
+"""
+
+# tag::COORDINATE[]
+from typing import NamedTuple
+
+class Coordinate(NamedTuple):
+
+    lat: float
+    long: float
+        
+    def __str__(self):
+        ns = 'N' if self.lat >= 0 else 'S'
+        we = 'E' if self.long >= 0 else 'W'
+        return f'{abs(self.lat):.1f}°{ns}, {abs(self.long):.1f}°{we}'
+# end::COORDINATE[]

05-record-like/typing_namedtuple/coordinates2.py

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+"""
+``Coordinate``: a simple ``NamedTuple`` subclass
+
+This version has a field with a default value::
+
+    >>> moscow = Coordinate(55.756, 37.617)
+    >>> moscow
+    Coordinate(lat=55.756, long=37.617, reference='WGS84')
+
+"""
+
+# tag::COORDINATE[]
+from typing import NamedTuple
+
+class Coordinate(NamedTuple):
+
+    lat: float                # <1>
+    long: float
+    reference: str = 'WGS84'  # <2>
+# end::COORDINATE[]

05-record-like/typing_namedtuple/nocheck_demo.py

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+import typing
+
+class Coordinate(typing.NamedTuple):
+
+    lat: float
+    long: float
+
+trash = Coordinate('foo', None)  # <1>
+print(trash)