Find all Class Helpers in Delphi at runtime using RTTI?

Question

Does the extended RTTI in Delphi 2010 offer a way to list defined Class and Record Helpers at run time?

As far as I know Delphi does not show a hint or warning when more than one class helper is defined for a class, class helper detection might be a helpful routine in 'quality assurance'.

p.s. of course I know I should never ever use third party components or libraries without source code, which would make it easy to grep class helpers.

Answer 1

Since class helpers only apply to a class based on what helper is "closest" in scope, a class simply cannot know that a helper exists. For example, you can create a class helper in your unit to "help" a class from another unit for which you have no source. The class in the other unit has no clue about any helpers. If it did have this knowledge, then it would have to be recompiled to take this into account... which leads to the next issue;

Consider this: You could have a class declared in one common unit that is used by many other units throughout your application. In each of those units you declare a new helper for this common class with different methods and "helper" functions. Since each unit knows nothing about the other units that also declare their own helper, there is, by design, no way to somehow coalesce all the helpers. Now consider that this common unit now lives across a pre-compiled package boundary.

Class helpers are seductive little heathens. They promise fame and fortune, but too often they rain down death and destruction... long after you've given yourself over to their wiles.

For this reason, their introduction into the language solved very specific problems, namely the ability to "appear" to introduce functionality into an existing framework. As long as you adhere the "one helper only" rule, and do not stray from that path, you may emerge relatively unscathed. Regardless, you will need to have the combined intestinal fortitude of Beowulf, Leonidas (of Sparta), and Frodo Baggins to navigate through these waters.

Given that, here on the RAD Studio team, we are loath to ever use a class helper where it can be avoided. And when we do use them, an appropriate phalanx is formed before we even begin...

There be dragons here...