| Re: Yet again, The Sky is Falling! [message #52940 is a reply to message #52872] |
Mon, 12 March 2007 15:04   |
Sven Geier
Messages: 17
Registered: July 2002
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Junior Member |
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mgalloy@gmail.com wrote:
> I'm talking about two parameters that are both passed a single named
> variable (like Paul's mypro example). While legal, I don't think this
> is a good technique for clear code.
>
...and as usual there's exceptions where this is a perfectly good thing to
do. I have a routine in front of me that dynamically improves a "guess" of
some number. It takes an input and an output parameter and in almost all
cases you want to give it the same variable there. Schematically like this
x = someOldGuess
improve,x,x
where "improve" takes the first "x" as its input, copies the values to a
local variable, performs a bunch of magic and returns the result in
the "second x". From the outside, the variable "x" simply has a new,
improved value (which is the purpose of "improve'). However, there can be
extreme cases where one might want to have a little more introspection and
where one might want to check the returned value before using it and in
that case one can make it
improve,x,y
if (some test here) then x=y
or such.
I second David's statement that one of the nice things about IDL is that one
can do all these weird things. As someone once said (about C++, I
think) "all the power and all the elegance of a hand grenade": It ain't
always pretty but it gets things done.
- S
--
http://www.sgeier.net
My real email address does not contain any "Z"s.
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