[Lazarus] Form in DLL

Michael Schnell mschnell at lumino.de
Thu May 3 09:56:19 CEST 2012

On 05/03/2012 07:36 AM, Michael Fuchs wrote:
> So, there are no interference betwenn the two Application objects?
While I do believe, that  it is possible to have two TApplication 
instances, one in the Main application and one in the DLL, I feel that 
there are a lot or problems that need to be handled.

In fact I once suggested that it would be very nice to have, if Lazarus 
would provide a "DLL/so Application" Widget Type", But I think it would 
be a lot of work to create  same in a decent way. So beware !

Besides the obvious benefit of "two main Forms", this additionally would 
allow for the (then duplicated) LCL GUI functions to take advantage of 
multiple processors.

Some of the problems are:
  - You need a dedicate "main"-thread for each TApplication instance, to 
allow communication with the OS GUI.
  - You need a common memory manager to allow for a decent communication 
between the main application an the DLL.
  - Communication between the two mainthreads needs to be done via a 
mechanism based on "Synchronize" and/or "QueueAsyncCall".

Rather hard stuff :) .


More information about the Lazarus mailing list