反射获取内部变量结果值

Question

In our reporting environment we have a method to get the DataSources, which is looking like this:

protected override IEnumerable<ReportDataSource> GetDataSources(IEnumerable<ReportParameter> parameters)
{
    return new List<ReportDataSource>
    {
        new ReportDataSource("DataSource1", GetDataSource1(parameters)),
        new ReportDataSource("DataSource2", GetDataSource2(parameters))
    };
}

The values from the methods called are just ICollections. My problem is, I need to know the internal Type of these collections for documentation-purposes, at best without having to invoke the method. I just need the calls they're making, I broke this down to the local variable via:

const string dataSourcesMethodName = "GetDataSources";

MethodInfo methodInfo = type.GetMethod(
    dataSourcesMethodName,
    BindingFlags.Instance | BindingFlags.NonPublic,
    Type.DefaultBinder,
    new[] { typeof(IEnumerable<ReportParameter>) },
    null);

    var methodBody = methodInfo.GetMethodBody();
    var variable = methodBody.LocalVariables.First(f => f.LocalType == typeof(IEnumerable<ReportDataSource>));

Is it even possible to get the information I need without invoking this method?

Answer 1

Simply put, you can't without executing the method... some examples (see http://goo.gl/8QN19K ):

C#:

public ICollection M1() {
    ICollection col = new List<string>();
    return col;
}

public ICollection M2() {
    ArrayList col = new ArrayList();
    col.Add("Hello");
    return col;
}

IL code locals:

.locals init (
    [0] class [mscorlib]System.Collections.ICollection,
    [1] class [mscorlib]System.Collections.ICollection
)

and

.locals init (
    [0] class [mscorlib]System.Collections.ArrayList,
    [1] class [mscorlib]System.Collections.ICollection
)

Compiling in Release mode it is even worse, the locals could totally disappear... See for example http://goo.gl/yvWZHR

In general those methods could use for example an ArrayList , so an untyped collection (as in the M2 method). Good luck finding the type of its elements without executing the method and parsing some elements.