PPG Application Design
18
PT Program Generator (PPG) v5.0
Creating Function Nodes
Once you’ve designed the basic program structure, the next step in generating
a portable program is to define each
Function Node. Function Nodes
are
frames or subroutines and are used to organize the steps and work of
Opera-
tion Nodes
. Most developers start by creating
Function Nodes
.
Frames
Frames
contain a set of program steps that are collected and ordered in a logi-
cal structure.
Frames
can consist of other frames, subroutines, and nodes.
Nodes are Linked together within the frame using Links.
Subroutines
Subroutines
contain nodes that execute program steps, much like
Frames
, but
they can be called from anywhere in the application. They should be self-con-
tained and perform functions that are used in multiple places in the applica-
tion. Use
Call
nodes to link
Subroutines
to the location within the
Operation
Node
or
Frame
where they will be called.
Using Your Flow Chart
Using the flow chart you created in
Application Structure on page 16
, list the
Frames
and
Subroutines
you will define. As a general guideline, if the func-
tion is used in multiple places, make it a
Subroutine
. Otherwise, it should be a
Frame
. Once all
Function Nodes
are created, define each step by creating the
Operation Nodes
.
Creating Operation Nodes
Each
Operation Node
represents a program step or work performed by the
application. After you have created the frames and subroutines, fill in the pro-
gram steps for each function node. Using the flow chart, create an appropriate
Operation Node
for each step in the
Frame
or
Subroutine
. There are nine dif-
ferent types of
Operation Nodes
to chose from, as shown in
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