[Tutor] Are you allowed to shoot camels? [kinda OT]

Alan Gauld alan.gauld at freenet.co.uk
Fri Feb 4 19:13:31 CET 2005

> What you are try to do is "execute a block of code based on the
value of
> a single statement."  if/elif doesn't do that and thereby introduces
> possibility of errors.

In that case the best solution is a dictionary jump table.
That is more maintainable than either and much faster too.
And its also shorter to write.
[Especially with lambdas :-)]

> Note that the logic intended is that "on-this."  So why force the
> programmer to rewrite it N times and thereby introduce the
> of N-1 typographical errors...

Thats a fair point although the dictionary solution avoids that.
OTOH such switches tend to proliferate thropugh code and become
a big source of maintenance headaches in their own right - multiple
update syndrome across multiple files potentially.

> Note that I've left out break.  I'm not convinced that
> fall-through is an important feature in switch and is
> usually the culpit in the cases of abuse.

The problem is its so hard to tell when fall though is
happening intentionally  or by accident because someone
forgot a break sytatement.

But when it comes to abuuse the fall through mechanism is one
of the worst offenders in C, its just too tempting to be
"clever" with it.

> This is also true for the ternary operator.  The desired logic is to
> assign the value of a variable based on the value of some other
> variable.

But its not its based on the value of an *expression*. If the
test could be limited to a single valiable value it might be
justified but its an arbitrary expression. That makes it a
conditional statement, which is most clearly represented
by an if/else... Well I think so :-)

> I also like Perl's unless statement but really prefer
> VBs DO/WHILE/UNTIL/LOOP constuct.  Nothing beats it for
> clarity of expression.

I won't argue on either point, Python's minimalist
approach - there's only one way to do it - means a
paucity of looping constructs - something I point
out in my tutorial. But I can live with it for the
other niceties it brings.

Alan G.

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