Interactive
Scripts:
Intermediate
Error Trapping
When requesting user input, it is imperative that
the users enter the data in the desired format.
Dropdown, radio buttons, and check boxes
provide the user with limited options. The Edit
Box and ACCEPT() Commands, however, allow
the users to enter data in a free flow manner.
Entering invalid data can cause the script to
crash or produce invalid results. In order to
avoid this, users should engage in a practice
known as Error Trapping.
The Error Trapping Principle
The way an error trap works is that it will repeat a
script until the conditions for acceptable data
are met. This generally means:
1) Define a flag to monitor the conditions.
2) Execute a subscript so long as the conditions
are not met.
3) At the end of the subscript, check to see if the
conditions are met. If they are, then change
the flag ending the script.
Example 1:
While writing a script, you wish to ask the
user for a minimum dollar amount. You
only want numerics, a maximum of one
period, and negative signs.
Script
ASSIGN v_flag = F
DO subscript WHILE v_flag = F
Subscript
V_flag = T
ACCEPT "Enter minimum amount" TO v_minimum
COM If the value entered contains anything other than a
COM numeric/negative sign/period then the flag will be set to zero
COM causing the subscript to be rerun and the script to pause with a
COM message to the user explaining what the problem is.
IF EXCLUDE(v_minimum, "0123456789- .") <> " " and
OCCURS(v_minimum, ". ")<=1 ASSIGN v_flag = F
IF v_flag = F PAUSE “Please use only numbers, periods, and negative
signs.”
Lists
Using one of the methods described above,
you’ve created a list. Using this list, you
want to plug it into a dropdown box asking
the user to select a value.
This is very easy to accomplish. As
dialogue boxes can be complex to write, it
is often easiest to use the ACL Dialogue
Wizard to write the skeleton for your script.
Dialogue script list:
DIALOG (DIALOG TITLE "User Dialog"
WIDTH 494 HEIGHT 159 ) (BUTTONSET
TITLE "&OK;&Cancel" AT 370 12
DEFAULT 1 ) (DROPDOWN TITLE
"variable1;variable2;variable3" TO
"DROPDOWN1" AT 24 84 DEFAULT 2 )
(TEXT TITLE "test" AT 24 52 )
Dialog Command broken down:
• DIALOG ---Invokes the Dialog Command
• (DIALOG TITLE "User Dialog" WIDTH 494 HEIGHT 159 ) ---Defines
the width and height of dialog box.
• (BUTTONSET TITLE "&OK;&Cancel" AT 370 12 DEFAULT 1 ) --Positions the “OK/Cancel” button at position over 370 spaces and
down 12.
• (DROPDOWN TITLE "variable1;variable2;variable3" ---this is the list
of items within the dropdown list.
• TO "DROPDOWN1" ---The default variable name assigned by ACL.
• AT 24 84 ---Locates the drop down at 24 over and 84 down.
• DEFAULT 2 ) ---Defines the default value as the second value in the
list. A field does not require a DEFAULT value.
• (TEXT TITLE "test" AT 24 52 ) ---Locates text at position 24 over
and 52 down.
Dialog Script project item
• DIALOG ---Invokes the Dialog Command
• (DIALOG TITLE "User Dialog" WIDTH 459 HEIGHT 159 ) ---Defines
the width and height of dialog box.
• (BUTTONSET TITLE "&OK;&Cancel" AT 370 12 DEFAULT 1 ) --Positions the “OK/Cancel” button at position over 370 spaces and
down 12.
• (ITEM TITLE "NCD" ---NCD indicates that the dropdown box will
include “N”umerics, “C”haracter” and “D”ate fields.
• TO "ITEM1" ---Item1 is the default variable name assigned by ACL.
• AT 48 60 WIDTH 255 ---The dropdown will appear 48 spaces over
and 60 down with a width of 255.
• DEFAULT "test" ) ---The default value will be “test.”
Data Normalization
When using interactive scripts, it is
often necessary to normalize the
data to ensure accurate data
analysis. This can concern both
the data contained within the field
and the description of the field
itself.
Modifying Data in Fields
Often times in order to perform an analysis,
the data must be normalized within the
fields themselves. The use of functions
such as UPPER() or ALLTRIM()
commands is much more important with
interactive scripts than it is with noninteractive scripts.