Include Dynamically Created Objects

Purpose

Including dynamic objects in your compiled application

Precursor

Please note that datawindow objects, bitmaps, and icons should be included in an application using a pbr (powerbuilder resource file). This document explains how to include powerbuilder object classes other than the datawindow object.

Whats the issue?

I quite often find I need to create objects dynamically in Powerbuilder, i.e. objects for which the datatype is unknown until runtime. There are many reasons for doing this, one of the more common is having a generic function to open a sheet in your application which takes a string with the sheet's classname.
Powerbuilder will quite happily cope with this situation at development time, and even at compilation time. However, it's not uncommon for developers to have problems with the executable producing unknown object errors when using these dynamic methods.

Solutions

There are 2 real solutions which you can use to include dynamically created objects in your application.

Solution 1 - Including the objects in PBDs

Create pbds for all the pbls which have the dynamic objects, tick the PBD checkbox next to the relevant pbls in the project painter. This should get rid of the unknown object errors in the compiled application.

Solution 2 - Including the objects in the actual EXE

Of course many people don't like PBDs, they can be very troublesome, particularly if you have many applications which have been built at different times. Using a PBD from another application can cause crashes, even if the code is the same in the other PBD!

So the solution is to include the dynamic objects by referencing them directly, but doing so in code which doesn't get executed. I find the best way is to create an event called, for instance ue_include, and write the code in there. A variation is to write a conditional statement which will not executed, for example IF 1=2 THEN ...

Example for Solution 2

You have sheets called w_sheet1, w_sheet2, and an object called nv_object1 which are created dynamically

Where to put this

It depends on your application really, if you're sharing the functionality between applications it can be worthwhile putting this code in the master application object, so that you don't reference objects which are irrelevant to the application itself. Of course this relies upon you remembering to include the objects in your application.

If the code is specific to an application, or the dynamic objects are always used, I would personally place the inclusion code within the object itself.

Quite often the best solution is to use a combination of both methods, and making sure there is good documentation in place to explain what's going on!

Details

Author:     Wayne Jones
Created:    16 April 2003
Works with: All versions