CODEWITHSUNDEEP
c#vb.netfunctionobject
Terry
Terry

Reputation: 5262

How to pass a function as an object instead of a function?

I'm trying to give a default value to the register property method. This required a function, but passed as an object(delegate?). Here's the code:

protected static propertydata registerproperty(string name, Type type, Func<object> createDefaultValue)
{
    return RegisterProperty(name, type, createDefaultValue, false, null);
}

I want to call that registerproperty method, but I don't know how I can do that in VB.net. I just need to pass along a new Person object and I thought this was the way to go:

Public Shared ReadOnly ItemsProperty As PropertyData = RegisterProperty("Items", GetType(IEnumerable(Of Person)), Function() new Person())

This is a function passed as a function, but I need it to pass as an object.

Any thoughts on this?

Upvotes: 1

Views: 193

Answers (3)

sporty
sporty

Reputation: 51

Sometimes, working with a sub instead of a function resolves the issue, we've solved some problems that way.

Public Shared ReadOnly ItemsProperty As PropertyData = RegisterProperty("Items", GetType(IEnumerable(Of Person)), Sub() new Person())

Upvotes: 1

Olivier Jacot-Descombes
Olivier Jacot-Descombes

Reputation: 112269

The parameter Func<object> createDefaultValue means that you have to pass a function which returns an object. You don't have to pass an object.

Function() new Person() is a lambda expression, which represents such a function in VB.

() => new Person() is the same in C#.

Your ItemsProperty As PropertyData will automatically call this function when a default value is required.

Upvotes: 0

Jay
Jay

Reputation: 6017

This should work even for older versions of the framework:

Public Shared Function whatever() As propertyData
    registerproperty("item", GetType(IEnumerable(Of Person)), AddressOf GetObject)
End Function

Public Shared Function GetObject() As Person
    return New Person
End Function

with VB 2008 or higher you can use what you have:

registerproperty("Item", GetType(IEnumerable(Of Person)), Function() New Person)

Upvotes: 1

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