ABAP_to_the_Future

10
ALV SALV Reporting Framework
report. You might have a report that’s a list of monsters, and you can select a
checkbox by a particular monster, and then click an icon at the top of the screen,
which displays a map showing the monster’ s location in real time. In a slightly
more realistic example, you might have a list of customers whose orders are going
to be delivered late, and you select a customer, and then click a button, which
triggers an outgoing phone call to the phone number stored in SAP ERP so that
you can tell them the bad news. Neither of those examples would have been feasible
10 years ago, which shows how far technology has come.
Anyway, you want to be able to pass in a list of these extra user commands into
your report object, and have extra buttons appear at the top of the screen, and
have extra options on the context menu the users get when they select a record
and right-click. A table of the structure STB_BUTTON is ideal for this purpose,
because it has fields for the name of the new command, what it should look like
(icon, button, etc.), and text description fields to tell the user what the button
does: a short description that appears next to the button and a longer description
that appears via hover text.
In a good OO program, this list comes from the application model, which says to
the controller something like, “Hello, here’s a list of commands I can respond to.
I’ll give you the descriptions and a rough guide to how they should look, but I’ll
leave the actual details to you.” The controller passes the instructions to the view
with a similar comment. This way, wh en a new and better view technology
comes along, the controller can cast aside the old view and run off with the new
younger one but still give it the exact same command list.
The actual table is passed in changing parameter CT_DATA_TABLE typed as a
generic table, due to the fact that the structure of the table to be displayed is different
for every report. This example uses a changing parameter for the technical
reason that some technologies want this table as a changing parameter and others
wants it as a pure importing parameter. A changing parameter is the lowest common
denominator; you can have a changing parameter and not change it, but you
can’t have an importing parameter and then try to change it in an OO method.
In order to code the INITIALIZE method, you have to split up the creation of the
view object and the initialization, because you create the view object, then link it
into the MVC framework, and only at a later date when you have the finished
report data from the model do you actually create the underlying report object.
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