warning CS0168: The variable 'el' is declared but never used?

[kellyatdentrix]

Suppose that I just want to count the elements in a collection, so I do
this:

int i = 0;
foreach (MyElement el in MyCollection)
{
i++;
}
return i;

Is there any way in the 2003 compiler to avoid the warning:
warning CS0168: The variable 'el' is declared but never used?

I don't want to turn off the warning (can't anyway in VS 2003) I want
to fix the code without doing something wasteful...

Thanks!

And yes, I do know that you could just get the length of the
collection... my real example is a bit more complex than that presented
here.

-Kelly

--------------------------------
From: Kelly Anderson

[Daniel O'Connell [C# MVP]]

<ke************ @gmail.com> wrote in message
news:11******** *************@z 14g2000cwz.goog legroups.com...

Bruce Wood wrote:

Could you give more details about the "real example"?

Trying to think of a situation in which you would want to iterate over
the members of a collection but not actually do anything with the
individual members is giving me a headache. If you could give more
details, perhaps it would help my dearth of imagination. :)

Ok, sure. In the real example, there is an iterator. The iterator is
incredibly complex, skipping items in the real collection depending on
a huge number of variables. I want to know how many items will be
iterated over prior to the iteration beginning for various reasons. So
basically, I'm wanting to know how many items there are, but Count
won't work because many items in the actual collection will be skipped
according to user preferences, and many other business rules.

So I want a Count, but based on how many items the iterator will visit,
not how many items are actually in the collection.

While its not a direct answer to your question, why not just filter the
collection down in successive layers? That will give you a complete
collection at the otehr end with all the benefits of a collection. I can't
help thinking that a complicated iterator is going to be hard to maintain
and pehaps a risky spot, performance wise.

[Jon Skeet [C# MVP]]

Otis Mukinfus <ph***@emailadd ress.com> wrote:

<snip>

Why do you want to get rid of the warning in the first place?

I don't know about Kelly, but I view warnings as errors - I don't allow
my code to compile with warnings. Because *some* warnings are
definitely significant, you want to make sure you don't have any of
those - and the easiest way of doing that is to ensure that there are
never any warnings at all.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[Otis Mukinfus]

On Thu, 9 Feb 2006 07:09:31 -0000, Jon Skeet [C# MVP]
<sk***@pobox.co m> wrote:

Otis Mukinfus <ph***@emailadd ress.com> wrote:

<snip>

Why do you want to get rid of the warning in the first place?

I don't know about Kelly, but I view warnings as errors - I don't allow
my code to compile with warnings. Because *some* warnings are
definitely significant, you want to make sure you don't have any of
those - and the easiest way of doing that is to ensure that there are
never any warnings at all.

Normally I would agree 100% Jon. But with that error I'd be tempted
to let it slide, or as many have suggested, do the process another
way. He is using foreach as convenience anyway (as we all do).

Couldn't one loop through each element of the list and check it's type
in order to do what he wants? There's probably a case to be made
against that too (speed comes to mind) ;o)

Otis Mukinfus
http://www.otismukinfus.com
http://www.tomchilders.com

[Jon Skeet [C# MVP]]

Otis Mukinfus <ph***@emailadd ress.com> wrote:

I don't know about Kelly, but I view warnings as errors - I don't allow
my code to compile with warnings. Because *some* warnings are
definitely significant, you want to make sure you don't have any of
those - and the easiest way of doing that is to ensure that there are
never any warnings at all.

Normally I would agree 100% Jon. But with that error I'd be tempted
to let it slide, or as many have suggested, do the process another
way. He is using foreach as convenience anyway (as we all do).
The trouble is that if you let even one warning slide, it's harder to
tell when you get more - especially when you then find that there are a
few other things that you might as well let slide to the same amount,
for instance. You soon get into the stage where you can't *really
easily* tell whether or not the code you've just added has introduced a
new warning. Much better to just be draconian to start with :)
Couldn't one loop through each element of the list and check it's type
in order to do what he wants? There's probably a case to be made
against that too (speed comes to mind) ;o)

More for duplication of code reasons, I'd say. It sounds like Kelly
already has that code somewhere, so we might as well make use of it
again...

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[kellyatdentrix]

> Couldn't one loop through each element of the list and check it's type

in order to do what he wants? There's probably a case to be made
against that too (speed comes to mind) ;o)

In this particular case, it's not an issue of type, it's an issue of
business object state.

Just to give a simplified taste of the problem, I'm iterating over
teeth and data about teeth in a mouth object, and I want to skip
missing teeth and such. I might also skip teeth (or certain information
about the tooth) based upon states of the user interface (stuff hidden
and such) or some pretty complex user preferences. Whether the tooth is
missing comes from yet another object, so I don't have a collection, I
have a set of business object states. I have six classes involved in
the iteration computation, many many hundreds of lines of code.

It's not one of the more simple cases you run into in the normal course
of dealing with objects. The actual logic is brutally complex. Just
GetNext is 43 lines of code. It's ugly stuff.

By the way, I really liked the solution of using the
enumerator/iterator directly. I'll probably just do that. Thanks!

-Kelly

[kellyatdentrix]

Otis Mukinfus wrote:

On Thu, 9 Feb 2006 07:09:31 -0000, Jon Skeet [C# MVP]
<sk***@pobox.co m> wrote:

Why do you want to get rid of the warning in the first place?

I don't know about Kelly, but I view warnings as errors - I don't allow
my code to compile with warnings. Because *some* warnings are
definitely significant, you want to make sure you don't have any of
those - and the easiest way of doing that is to ensure that there are
never any warnings at all.

Normally I would agree 100% Jon. But with that error I'd be tempted
to let it slide, or as many have suggested, do the process another
way. He is using foreach as convenience anyway (as we all do).

Couldn't one loop through each element of the list and check it's type
in order to do what he wants? There's probably a case to be made
against that too (speed comes to mind) ;o)

The problem is that these spurious warnings can mask serious issues. If
I get rid of the spurious warnings, then I can see the warnings that I
care about. If there are spurious warnings, then one I care about could
be lurking in the list, and I wouldn't see it as something that needed
immediate attention.

-Kelly

[Otis Mukinfus]

On 9 Feb 2006 14:05:33 -0800, "ke************ @gmail.com"
<ke************ @gmail.com> wrote:

Otis Mukinfus wrote:

On Thu, 9 Feb 2006 07:09:31 -0000, Jon Skeet [C# MVP]
<sk***@pobox.co m> wrote:

>> Why do you want to get rid of the warning in the first place?
>
>I don't know about Kelly, but I view warnings as errors - I don't allow
>my code to compile with warnings. Because *some* warnings are
>definitely significant, you want to make sure you don't have any of
>those - and the easiest way of doing that is to ensure that there are
>never any warnings at all.

Normally I would agree 100% Jon. But with that error I'd be tempted
to let it slide, or as many have suggested, do the process another
way. He is using foreach as convenience anyway (as we all do).

Couldn't one loop through each element of the list and check it's type
in order to do what he wants? There's probably a case to be made
against that too (speed comes to mind) ;o)

The problem is that these spurious warnings can mask serious issues. If
I get rid of the spurious warnings, then I can see the warnings that I
care about. If there are spurious warnings, then one I care about could
be lurking in the list, and I wouldn't see it as something that needed
immediate attention.

-Kelly

All good reasoning gentlemen.

Otis Mukinfus
http://www.otismukinfus.com
http://www.tomchilders.com