Helproutines have specific characteristics to facilitate the processing of help requests. They may be used to implement complex and interactive help systems. They are created with the program editor.
This document covers the following topics:
A Natural user can invoke a Natural helproutine either by entering the help character in a field, or by pressing the help key (usually PF1). The default help character is a question mark (?).
The help character must be entered only once.
The help character must be the only character modified in the input string.
The help character must be the first character in the input string.
If a helproutine is specified for a numeric field, Natural will allow a question mark to be entered for the purpose of invoking the helproutine for that field. Natural will still check that valid numeric data are provided as field input.
If not already specified, the help key may be specified with the
SET KEY statement:
SET KEY PF1=HELP
A helproutine can only be invoked by a user if it has been specified in the program or map from which it is to be invoked.
A helproutine may be specified:
in a program: at statement level and at field level;
in a map: at map level and at field level.
If a user requests help for a field for which no help has been specified, or if a user requests help without a field being referenced, the helproutine specified at the statement or map level is invoked.
A helproutine may also be invoked by using a
REINPUT USING
HELP statement (either in the program itself or in a
processing rule). If the REINPUT USING HELP statement contains a
MARK
option, the helproutine assigned to the MARKed field is invoked.
If no field-specific helproutine is assigned, the map helproutine is
invoked.
A REINPUT
statement in a helproutine may only apply to INPUT statements within the same
helproutine.
The name of a helproutine may be specified either with the session
parameter HE of an
INPUT statement:
INPUT (HE='HELP2112')
or using the extending field editing facility of the map editor (see Creating Maps and the Editors documentation).
The name of a helproutine may be specified as an alphanumeric constant or as an alphanumeric variable containing the name. If it is a constant, the name of the helproutine must be specified within apostrophes.
Processing of a helproutine can be stopped with an
ESCAPE
ROUTINE statement.
Be careful when using END OF
TRANSACTION or BACKOUT TRANSACTION statements
in a helproutine, because this will affect the transaction logic of the main
program.
A helproutine can access the currently active global data area (but it cannot have its own global data area). In addition, it can have its own local data area.
Data may also be passed from/to a helproutine via parameters. A
helproutine may have up to 20 explicit parameters and one implicit parameter.
The explicit parameters are specified with the HE operand after
the helproutine name:
HE='MYHELP','001'
The implicit parameter is the field for which the helproutine was invoked:
INPUT #A (A5) (HE='YOURHELP','001')
where 001 is an explicit parameter and #A is
the implicit parameter/the field.
This is specified within the DEFINE DATA PARAMETER
statement of the helproutine as:
DEFINE DATA PARAMETER 1 #PARM1 (A3) /* explicit parameter 1 #PARM2 (A5) /* implicit parameter END-DEFINE
Please note that the implicit parameter (#PARM2 in the
above example) may be omitted. The implicit parameter is used to access the
field for which help was requested, and to return data from the helproutine to
the field. For example, you might implement a calculator program as a
helproutine and have the result of the calculations returned to the field.
When help is called, the helproutine is called before the data are passed from the screen to the program data areas. This means that helproutines cannot access data entered within the same screen transaction.
Once help processing is complete, the screen data will be refreshed: any
fields which have been modified by the helproutine will be updated - excluding
fields which had been modified by the user before the helproutine was invoked,
but including the field for which help was requested. Exception: If
the field for which help was requested is split into several parts by dynamic
attributes (DY session
parameter), and the part in which the question mark is entered is
after a part modified by the user, the field content will not be
modified by the helproutine.
Attribute control variables are not evaluated again after the processing of the helproutine, even if they have been modified within the helproutine.
The equal sign (=) may be specified as an explicit parameter:
INPUT PERSONNEL-NUMBER (HE='HELPROUT',=)
This parameter is processed as an internal field (format/length A65) which contains the field name (or map name if specified at map level). The corresponding helproutine starts with:
DEFINE DATA PARAMETER 1 FNAME (A65) /* contains 'PERSONNEL-NUMBER' 1 FVALUE (N8) /* value of field (optional) END-DEFINE
This option may be used to access one common helproutine which reads the field name and provides field-specific help by accessing the application online documentation or the Predict data dictionary.
If the field selected by the help character or the help key is an array element, its indices are supplied as implicit parameters (1 - 3 depending on rank, regardless of the explicit parameters).
The format/length of these parameters is I2.
INPUT A(*,*) (HE='HELPROUT',=)
The corresponding helproutine starts with:
DEFINE DATA PARAMETER 1 FNAME (A65) /* contains 'A' 1 FVALUE (N8) /* value of selected element 1 FINDEX1 (I2) /* 1st dimension index 1 FINDEX2 (I2) /* 2nd dimension index END-DEFINE ...
The size of a help to be displayed may be smaller than the screen size. In this case, the help appears on the screen as a window, enclosed by a frame, for example:
*******************************************************************************
PERSONNEL INFORMATION
PLEASE ENTER NAME: ?_________________
PLEASE ENTER CITY: __________________
+---------------------------+
! !
! Type in the name of an !
! employee in the first !
! field and press ENTER. !
! You will then receive !
! a list of all employees !
! of that name. !
! !
! For a list of employees !
! of a certain name who !
! live in a certain city, !
! type in a name in the !
! first field and a city !
! in the second field !
! and press ENTER. !
*******************! !*******************************
+---------------------------+
Within a helproutine, the size of the window may be specified as follows:
by a FORMAT
statement (for example, to specify the page size and line size: FORMAT
PS=15 LS=30);
by an INPUT USING
MAP statement; in this case, the size defined for the map (in
its map settings) is used;
by a DEFINE
WINDOW statement; this statement allows you to either
explicitly define a window size or leave it to Natural to automatically
determine the size of the window depending on its contents.
The position of a help window is computed automatically from the
position of the field for which help was requested. Natural places the window
as close as possible to the corresponding field without overlaying the field.
With the DEFINE WINDOW statement, you may bypass the automatic
positioning and determine the window position yourself.
For further information on window processing, please refer to the
DEFINE WINDOW
statement in the Statements documentation and the terminal
command %W in the
Terminal Commands documentation.