Generic type factory

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I'm unable to call the Create<> function due to compile errors.
Any ideas?

enum ReportTypes
{
    Report1,
    Report2,
    Report3 
}

abstract class Report
{
    protected abstract bool Run();
}

class Report1 : Report
{
    protected override bool Run()
    { return true; }
}

class Report2 : Report
{
    protected override bool Run()
    { return true; }
}

class Report3 : Report
{
    protected override bool Run()
    { return true; }
}
class ReportFactory
{
    private static Dictionary<ReportTypes, Type> Reports = new Dictionary<ReportTypes, Type>()
    {
      {ReportTypes.Report1, typeof(Report1) },
      {ReportTypes.Report2, typeof(Report2)},
      {ReportTypes.Report3, typeof(Report3)},
    };

    static Report Create<T>() where T : Report, new()
    {
        return new T();
    }

    public static Report GetReport(ReportTypes reportType)
    {
        //Unable to get this line to work
        return ReportFactory.Create<Reports[reportType]>();
    }

}

What I have tried:

return ReportFactory.Create<typeof(Reports[reportType])>();

and

return ReportFactory.Create<Reports[reportType].GetType()>();

I know I can simply do this but, wanted to use the static Create function instead.

Report = (Report)ClassFactory.Create(Reports[reportType].GetType());

Posted 2-Jan-18 3:50am

-Dr_X-

Updated 2-Jan-18 4:30am

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2 solutions

Solution 3

You can do this using reflection

public static Report GetReport(ReportTypes reportType)
{
    Type t = Reports[reportType];

    MethodInfo method = typeof(ReportFactory)
        .GetMethods(BindingFlags.Static | BindingFlags.NonPublic)
        .First(m => m.Name == "Create");

    MethodInfo genericMethod = method.MakeGenericMethod(t);
    return (Report)genericMethod.Invoke(null, null);
            
}

Posted 2-Jan-18 4:30am

F-ES Sitecore

Comments

Thomas Daniels 2-Jan-18 12:54pm

+5

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Thomas Daniels · Accepted Answer · 2018-01-02T03:56:00

Solution 1

They way you're using generics, isn't supported in C#. Between < and >, the name of a type is expected, not a Type object that isn't known at compile-time.

To create something based on a Type object, you can use Activator.CreateInstance[^].

Posted 2-Jan-18 3:56am

Thomas Daniels