Load imports outside/inside of namespace if there is only one?

Question

I got ONLY 1 Namespace and these 2 different codes :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.IO;

namespace blabla
{
    [...]
}

and

namespace blabla
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Reflection;
    using System.IO;

    [...]
}

I don't see any difference at all here but it that really the case ? I mean about performance or whatever

See http://blogs.msdn.com/b/ericlippert/archive/2007/06/25/inside-or-outside.aspx — Jon Skeet, Jan 27 '12 at 15:25
More info here: http://stackoverflow.com/questions/125319/should-usings-be-inside-or-outside-the-namespace — vc 74, Jan 27 '12 at 15:28

score 2 · Accepted Answer · answered Jan 27 '12 at 15:26

there is no difference in terms of performance. Namespace is the way of code organization and scoping. So in your case, using states will be defined globally in first snippet and inside namespace for the second. In both cases, physical assemblies will be referenced equally in both cases.

score 1 · Answer 2 · answered Jan 27 '12 at 15:28

It's a matter of scope declaration.

In the first case you are "declaring" the using statements on a file-level which means that they are valid for several namespaces you are able to declare in this file.

In the second case your using statements are only valid inside the defined (namespace-)scope.

Hope this helps :)

Load imports outside/inside of namespace if there is only one?

2 Answers2