ch02

ch02/namedtuple.py

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+# namedtuple.py
+
+
+# the problem
+>>> vision = (9.5, 8.8)
+>>> vision
+(9.5, 8.8)
+>>> vision[0]  # left eye (implicit positional reference)
+9.5
+>>> vision[1]  # right eye (implicit positional reference)
+8.8
+
+
+# the solution
+>>> from collections import namedtuple
+>>> Vision = namedtuple('Vision', ['left', 'right'])
+>>> vision = Vision(9.5, 8.8)
+>>> vision[0]
+9.5
+>>> vision.left  # same as vision[0], but explicit
+9.5
+>>> vision.right  # same as vision[1], but explicit
+8.8
+
+
+# the change
+>>> Vision = namedtuple('Vision', ['left', 'combined', 'right'])
+>>> vision = Vision(9.5, 9.2, 8.8)
+>>> vision.left  # still correct
+9.5
+>>> vision.right  # still correct (though now is vision[2])
+8.8
+>>> vision.combined  # the new vision[1]
+9.2