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up vote 97 down vote favorite
9

Is it possible to make this code a little more compact by somehow declaring the 2 variable inside the same using block?

using (var sr = new StringReader(content))
{
    using (var xtr = new XmlTextReader(sr))
    {
        obj = XmlSerializer.Deserialize(xtr) as TModel;
    }
}
share|improve this question
4  
Don't use new XmlTextReader(). Use XmlReader.Create() –  John Saunders Feb 22 '12 at 13:48
1  
@JohnSaunders why? –  Antony Scott Feb 22 '12 at 13:51
9  
new XmlTextReader() has been deprecated since .NET 2.0. By using XmlReader.Create(), you will get the best derived XmlReader class possible, as opposed to just the one XmlTextReader class. –  John Saunders Feb 22 '12 at 13:53
    
@JohnSaunders thanks for clarifying that. I've changed my code now. –  Antony Scott Feb 22 '12 at 13:54

2 Answers 2

up vote 168 down vote accepted

The accepted way is just to chain the statements:

using (var sr = new StringReader(content))
using (var xtr = new XmlTextReader(sr))
{
    obj = XmlSerializer.Deserialize(xtr) as TModel;
}

Note that the IDE will also support this indentation, i.e. it intentionally won’t try to indent the second using statement.

share|improve this answer
    
Does this use the one-liner-no-braces rule to scope the statements within each other, or actually compile into some sort of chain? –  ssube Feb 22 '12 at 13:50
5  
@MD.Unicorn Yes, exactly. This is intentional – this is the most concise way C# offers: removing the parentheses and omitting the indentation. Notice how the IDE offers explicit support for this (otherwise it would indent the second statement). –  Konrad Rudolph Feb 22 '12 at 13:53
1  
@KonradRudolph My question is kind of confusing, but I'm asking if this is actually a discrete language feature designed for multiple usings, or just the same as if (x) if (y) { z; }. I think your comment answers that, though; I'm reading it as the latter? –  ssube Feb 22 '12 at 14:21
1  
@peachykeen Yes, it’s definitely not a discrete language feature, merely nested blocks. The IDE does treat it specially for the purpose of indentation though. –  Konrad Rudolph Feb 22 '12 at 14:40
2  
I really wish C# had a form of using that didn't begin a new block, but instead disposed the variables at the end of the block in which they're declared, something like: { using var x = new Reader(); x.Read(); } –  Stefan Dragnev Sep 5 '14 at 6:24
up vote 41 down vote

Edit

The following only works for instances of the same type! Thanks for the comments.

This sample code is from MSDN:

using (Font font3 = new Font("Arial", 10.0f), font4 = new Font("Arial", 10.0f))
{
    // Use font3 and font4.
}
share|improve this answer
4  
This only work when variables are of the same type. –  MD.Unicorn Feb 22 '12 at 13:54
1  
that only seems to work if both objects are of the same type –  Antony Scott Feb 22 '12 at 13:55

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