ParameterInfo.ParameterType is "SqlBytes&", how to compare with typeof()

Question

I'm writing an automated SQLCLR deployment tool and I'm using reflection to discover the procedures and functions that have to be declared. So I'm using code like this to build the T-SQL needed to deploy the assembly methods:

...
if (p.ParameterType == typeof(string))
{
   sql = "nvarchar(4000)";
}
...

But this method contains an parameter declared in C# as out SqlBytes bytes and the ParameterType is SqlBytes&. I cannot use typeof(SqlBytes&) for comparison, because is invalid syntax. So I'm a bit puzzled what exactly is the SqlBytes& type, and if there is a way to produce the typeof for it. I know I can resort to types name (ie. strings) comparison instead, that is not my the question, I'm more curious what is such a type with &, seems like a C++ reference type, but I reckon in +10 years of working with .Net I've never noticed them.

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Marc Gravell · Accepted Answer · 2012-11-14 09:45:59Z

6

SqlBytes& is exactly the same as out SqlBytes (and ref SqlBytes, as it happens). Basically, out and ref are implemented identically, as a reference, by-reference. If you are using reflection and you currently have a Type instance, you can get the by-reference version by using:

Type type = ...
Type byRefType = type.MakeByRefType();

and rather confusingly, to get back to the non-by-ref version:

Type origType = byRefType.GetElementType();

(I suspect they probably just hacked that into an existing method, frankly)

answered Nov 14, 2012 at 9:45

Marc Gravell

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2 Comments

Remus Rusanu Over a year ago

Got it, typeof(SqlBytes).MakeByRefType()

Marc Gravell Over a year ago

@RemusRusanu yup; I've edited to show both by-val <===> by-ref operations

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