ObjGuard

Sometimes it happens that I would like to convert a Delphi object to an interfaces. Interfaces offer some advantages.
On the one hand you can handle different objects that are not derived from a common hierarchy but share the same methods.
On the other hand interfaces are reference counted. You can use the reference counting as a poor man’s garbage collection.

Normally objects that are interfaced are derived from TInterfacedObject.
Let’s have a look at the implementation of TInterfacedObject in Delphi XE3.

You can see two things:

  1. Every interfaced object has to implement IInterface.
  2. EMBT will introduce a real garbage collection but currently a TInterfacedObject is simply reference counted.

Normally you have to decide whether an object is interfaced or not if you are implementing it, not if you are using it.
That’s why I introduced a small wrapper class for an object. The wrapper class is interfaced and offers full access to the underlying object.

This makes the use of the object very simple. Just create an instance of the ObjGuard and the resulting interface offers access to the underlying object.
You can use it for example in records which don’t offer a destructor so that there must be a way to destroy object fields.

This entry was posted in Tips and Tricks and tagged . Bookmark the permalink.

One Response to ObjGuard

  1. Pingback: Anonymous

Leave a Reply

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload CAPTCHA.