Title: Component Serialization
Question: Serialization is the process of saving a component state (To a file of stream). Delphi provides a nice infrastructure for serialization of components (The DFM Way). But how do we utilize this infrastructure to the fullest? What are the limitations?
Answer:
Introduction:
In order to understand serialization, we need to define what serialization is, what we want to save (the component state) and how do we use the mechanism if it exists. Only after understanding those concepts, we can continue to learn how to write components to use this infrastructure.
Serialization: I define serialization components as the process of taking a component, saving the component state, so we can reconstruct another component later that is identical to the original component. I do not know if there is a formal definition to serialization, and my definition my not be the best, but for this article, it is enough. An object that can be serialized is sometimes called persistent object. In Delphi, all components are by default persistent (with some limitations Ill talk about later in this article).
Component State: A Component state is what distinguishes a component from another component of the same type. If two components have the same state, we can replace one with the other without any change in the application. One can say that the state of a component is the algebraic sum of its properties.
Serializing a component in Delphi is a simple process, using the stream classes. To save a component to some media, all we need to do is create the appropriate stream, and save the component to the stream. In order to load the component, we need only to create the stream object, and then read the component.
Example of saving a component to file:
procedure TForm1.SaveComponent;
Var
Stream: TFileStream;
begin
Stream := TFileStream.Create('c:\temp\mycomponent.dat', fmCreate);
try
Stream.WriteComponent(MyComponent);
finally
Stream.Free;
End;
end;