How do I override TRichEdit.Lines.Add ?

Posted on 2011-02-10
Last Modified: 2012-05-11
I need to override TRichEdit.Lines.Add in order to do some processing there, before adding the text in the RichEdit. How can I do that? Can I do that directly?
Question by:cubic77
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
LVL 32

Expert Comment

by:Ephraim Wangoya
ID: 34864597

Not exactly, the TStrings.Add method itself can be overriden but TRichEdit is not structured in such a way to allow you to do that easily

you can go around it by using the code as follows in your form unit
  TRichEdit = class(ComCtrls.TRichEdit)
    function Add(const AString: string): Integer; 
  TForm1 = class(TForm)


function TRichEdit.Add(const AString: string): Integer;
  NewString: string;
  //do something with the string and assign the new value to NewString
  Result := Lines.Add(NewString);

Open in new window

LVL 32

Expert Comment

by:Ephraim Wangoya
ID: 34864613
So instead of using

you will use

Author Comment

ID: 34864789
Thanks, but I already implemented exactly the same thing. Until I get the answer to my original question, this solution is acceptable but far from good. Why I don't consider it a GOOD solution? Because I have to remember that I have to use the exception (RichEdit.Add) instead of the normal method.

So, probably in 3-4 months I will accidentally use RichEdit.Lines.Add and I will start to wonder why my RichEdit is not working as expected.
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!


Author Comment

ID: 34864822
Actually this solution will became GOOD if the is a way to make the original method (lines.add) not to work anymore. In this case obviously I will see the error message while trying to use it and I will probably remember to use the new method.
LVL 32

Accepted Solution

Ephraim Wangoya earned 500 total points
ID: 34864849
In that case you will have to encapsulate the TRichEdit in a new control, then expose the public methods of TRichEdit and install that control in your component palette.

Then replace all your TRichEdit controls with the new one.

I can show you how to do that, but right now I'm working on something

Author Comment

ID: 34864914
> I can show you how to do that, but right now I'm working on something
No. I got it. Thanks.

I also had that idea. What I actually wanted was to see if there is any way to override (for real) the Add method.

Featured Post

[Live Webinar] The Cloud Skills Gap

As Cloud technologies come of age, business leaders grapple with the impact it has on their team's skills and the gap associated with the use of a cloud platform.

Join experts from 451 Research and Concerto Cloud Services on July 27th where we will examine fact and fiction.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.

627 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question