Ben Finney wrote:
Peter Pearson <ppear...@nowhere.invalid> writes:
Hey, that's a cute example, but . . . what a trap! Is it possible to
document the use-the-object-not-the-string requirement loudly enough
that people won't get caught?
Don't use strings for such values. The data isn't going to be used, so
there's no sense using a semantically rich data type like a string.
Instead, use an ‘object’ instance; then, the only way to get a binding
that will compare equal is to use the very object itself.
FORWARD = object()
BACKWARD = object()
Strings may have their use, most of the time providing a string
representation of the object, here is an example:
FORWARD = object()
print 'moving %s' % FORWARD
> moving <object object at 0xb7dab5a8>
Another approach using strings:
class Direction:
FORWARD = 'forward'
print "moving %s' % Direction.FORWARD
> moving forward
Note that
Direction.FORWARD is Direction.FORWARD
is safe and will return True.
JM
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