Argument Modifiers: 'ref', 'out', 'params' and 'this'

'Russell Mull' on Sun, 12 Aug 2007 03:56:49 GMT, sez:

'params' is indeed woefully underused, though I'm not sure why. I see 'ref' sometimes, often used where 'out' should have been. And you can't really blame people for missing out out 'this', as that version of the language isn't exactly *released* yet...

'Zooba' on Sun, 12 Aug 2007 06:58:32 GMT, sez:

The 'this' modifier is mindblowing. 'params' is not. It's been around since old-style VB in an almost identical form and the concept for even longer. The reason the C calling convention (parameters pushed onto the stack in reverse order, caller cleans up) was invented was to support this. It really is nothing special.

I also like 'ref' and 'out', especially the distinction between the two, though it would be nice if there were a way to pass a null reference (though then we're back where we started with pointer parameters... not that I have a problem with that either).

'Buckley' on Sun, 12 Aug 2007 12:03:15 GMT, sez:

Erm, So what is so special about the keywword "this".

I suppose you aren't talking about this in the way that it reduces the scope to the object you are programming in cause the feature hasn't been releases I read in the comments.

Can you clarify this?

'Thomas Eyde' on Sun, 12 Aug 2007 12:06:52 GMT, sez:

I tend to avoid out/ref, as I feel a method's results should be returned as an assignment, not via its parameters.

A lot of out/ref parameters just confuse me. Add a return value to the mix, and I usually fail to understand what the method is supposed to do.

'Adel' on Sun, 12 Aug 2007 16:01:49 GMT, sez:

I know that you are talking mainly about "this" but isn't using structures for multiple return values is better than using multiple out?

'Steve' on Mon, 13 Aug 2007 08:04:08 GMT, sez:

With the "this" keyword and some of the other changes (like the implicit typing) it seems that C# is moving slowly and crabwise from Java to JavaScript.

'Andrew Webb' on Mon, 13 Aug 2007 08:23:33 GMT, sez:

'ref' is essential. FxCop will complain if you have the effrontery to use 'out', and suggests that you find another way. 'this' is still in the future (for me at any rate since I usually avoid betas and CTPs).

'lb' on Mon, 13 Aug 2007 09:03:58 GMT, sez:

>FxCop will complain if you have the
>effrontery to use 'out', and suggests
>that you find another way

really? wow.

The danger there is that someone will simply change out to ref, thus forcing users to initialise the variable and pass in a reference when the param is always created within the given method.

I hate examples where the best way to avoid a warning is to write uglier code.

I think the use of 'out' as in TryParse is decent. But also -- i just googled the topic and wow some people don't like 'out' at all.


Here's a codeproject link

http://www.codeproject.com/useritems/alternative_2_out_keyword.asp

'Andrew Webb' on Mon, 13 Aug 2007 12:40:39 GMT, sez:

Leon,

Here's the Microsoft FxCop rule regarding out parameters:-

http://msdn2.microsoft.com/en-us/library/ms182131(VS.80).aspx

Note the Community Content at the bottom, which fits in with your comment on TryParse.

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