how one could use dynamic dialogs, reflect and RECORD methods to build generic dialogs in Genero.
A detailed discussion about the techniques used here can be found at https://4js.com/files/documents/wwdc20/2_Tuesday/2_Tuesday_Leo.pdf.
sDADyn.4gl implements a reusable combination of DISPLAY ARRAY/INPUT and CONSTRUCT with dynamic dialogs and a callback mechanism via Interfaces into application code.
customers.4gl,orders.4gl and items.4gl use one and the same sDADyn dialog with different array types and different callbacks.
(sDADyn is an acronym for 'singular DISPLAY ARRAY dynamically created').
ccustomers.4gl,corders.4gl and citems.4gl show (almost) the same feature set implemented using classic DISPLAY ARRAY/INPUT/CONSTRUCT combinations.
The abstraction level in the code using the new dialog type is higher, the re usage level is higer and less code lines are needed in the application code.
Of course the code of the library has a cost, currently around 1 kLOC.
| File | Number Of Lines |
|---|---|
| ccustomers.4gl | 228 |
| customers.4gl | 107 |
| corders.4gl | 214 |
| orders.4gl | 80 |
| citems.4gl | 200 |
| items.4gl | 50 |
| sDADyn.4gl | ca 1000 |
Run
$ make run
to run the implementation using generic code. You get a simple list for 3 DB tables, each DB table has slightly other constraints to manage. Both display and input of data is possible.
Run
$ make crun
to run the implementation using classic static Genero dialogs. For simplicity the demo uses a SQLite database, you can however easily switch to Postgres or Informix.