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Why static typed languages are sometimes better.

David Bolen db3l at fitlinxx.com
Fri Jul 2 03:56:43 EDT 2004 
Roy Smith <roy at panix.com> writes:

> Amazingly, the test passed (that means I'm done, right?).  Well, it took 
> me a moment to realize that the only thing I ever do with the argument 
> in the current version is use it as a dictionary key.  (...)

Note that independent of the static v.  dynamic question, to answer
your question, no, the test passing doesn't mean you're done - at
least not if you're following a TDD approach.  In TDD, the first step
is to write a _failing_ test.  If the test you write doesn't initially
fail, that's a red flag that should be examined.  Now, it may turn out
the test is ok, the code is in fact ok, or even that the new test is
superfluous.  But it also may mean that the test is incomplete or that
it exposes something the code was previously doing that needs
adjusting.

In this case, if the only code that ever accessed the key to the
dictionary was your routine that was passing the new test, you may in
fact be done, since just storing the tuple in the dictionary still
satisfies your tests.  Conversely if the tuple should result in
distinct dictionary entries, then presumably that's what your test
should be validating, so something may be missing from the test to
enforce the desired behavior.

In any event, the lack of a failure should immediately make you study
the situation, as you obviously did, and figure out just what is going
on.

-- David
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