如何从函数中调用重载方法并在C＃中传递不同的参数类型

Question

I have two overloaded methods as below:

Render(PDFTable table)
Render(PDFText text)

I have to call these methods from another method inside a for..each loop and pass the parameters as below:

foreach (var item in sectionPDF.sectionElements)
{
    if (item.GetType().Equals(typeof(PDFTable)))
    {
        Render((PDFTable)item);
    }
    else if (item.GetType().Equals(typeof(PDFText)))
    {
        Render((PDFText)item);
    }
}

I would like to know, if there is any way to remove the if..else statements and dynamically resolve the type? Thanks in advance.

Answer 1

No, there isn't. C# doesn't support virtual dispatch based on argument type. Overload resolution is a purely compile-time matter. Hence you have to make the decision yourself, either the way you are doing it now, by using some form of a decision table, using a provider class that makes the decision, whatever else fits your software design.

Answer 2

You can use dynamic . First declare a method like this:

void RenderDispatch(dynamic item)
{
    Render(item);
}

Render((PDFTable)
Render((PDFText)

Then in the foreach :

foreach (var item in sectionPDF.sectionElements)
{
    RenderDispatch(item);
}

The runtime take care to call the correct override.

Beware that dynamic incurs in performance issue.

Answer 3

You can make your "Render" method generic:

void Render<T> (T item)
{
    //your stuff here
}

then:

foreach (var item in sectionPDF.sectionElements)
{
    Render(item);
}