About "protected virtual void DataPortal_Fetch(object criteria)" in ReadOnlyListBase

foxhard posted on Sunday, May 13, 2012

Hi,

I have see several examples of implementation of ReadOnlyList classes. But the fetch method is like this:

private void DataPortal_Fetch(SomeCriteriaClass criteria)

{...}

But, if inside ReadOnlyListBase there is the method: "protected virtual void DataPortal_Fetch(object criteria)" . Is there some performance issue if I use override method inside my inplementation like this:

protected override DataPortal_Fetch(object criteria)

{ 

     SomeCriteriaClass someCriteria = (SomeCriteriaClass)criteria;

}

JonnyBee replied on Monday, May 14, 2012

CSLA internally relies on reflection to make a dynamic call into the object.

So take f.ex a class that have several criteria classes:

private void DataPortal_Fetch(SomeCriteriaClass1 criteria)
{  ...   }

private void DataPortal_Fetch(SomeCriteriaClass2 criteria)
{  ...   }

private void DataPortal_Fetch(SomeCriteriaClass3 criteria)
{  ...   }

The DataPortal_Fetch all have a similar signature with one object as input.
Rather than having 3 Fetch methods we prefer to have on method and test for the actual criteria type.

protected override DataPortal_Fetch(object criteria)
{
     // Your code should check for the type of Criteria object.
}

That said, CSLA will check for

• strongly typed methods first then
• method with the correct number of parameter (and some fuzzy logic if finding multiple methods).
• the default name 

So this is not so much about performance as for coding style.

foxhard replied on Monday, May 14, 2012

Thanks Jonny