The callback events an object can raise.

Valid Values

An integer code combining the following values:

Remarks

Only resizable windows can have menus.

Example: If the object has to raise a GotFocus event and a Click event, the WdgCallbacks would contain (2 + 64) = 66.

About Functional Expressions

The software provides a host of built-in functions that process given arguments in a variety of ways. An expression consisting of a function and its arguments (typically, value expressions) is called a functional expression.

Examples of functional expressions are

General Performance

Functions are a special class of operator, but they perform much like arithmetic operators; they take one or more given values, perform an operation using those values, and return a result. The value of the result depends on the function.

The function’s arguments are similar to the arithmetic operands. Like arithmetic operands, the arguments can consist of literals or value expressions, including other functional and arithmetic expressions as shown in the following example:

$absolute(-7)

The functional expression shown above consists of the argument -7 and the function keyword $absolute. The function $absolute returns the absolute (i.e., unsigned) value of its argument (in this case, 7).

Complex Arguments

If the argument is a complex expression, the argument is evaluated before the function is applied. For example, in the expression

$absolute(6-11)

the arithmetic expression 6-11 is evaluated first, yielding $absolute(-5). Then the final result (5) is determined.

Functional expressions can act as arguments to other functions. For example, the expression

$toupper($substring(‘abcdef’,2,3))

evaluates to

$toupper(‘bcd’)

which in turn evaluates to

‘BCD’

Data Type of Arguments and Results

Each function expects arguments of a certain data type; however, the function accepts arguments of any data type and appropriately converts any argument that does not conform to the expected type.

A character literal is any string of characters enclosed in quotation marks as shown in the following example:
‘This is a character string.’
“This is a character string, too.”
For convenience, you can enter character literals without the delimiting quotation marks; however, quotation marks are required in some situations. The rules for using quotation marks are described in Quotation Marks.
Valid and Invalid Literals
The following are examples of valid literals:
‘abc’
Is a character string.
‘ab”C’
Is a character string.
”
Is a null string.
3.14159
Is a number literal.
9
Is a number literal.
‘10.99’
Is a character string.
‘John\’s toy boat’
Is a character string.
‘ABCd_EfG’
Is a character string.
‘1234A’
Is a character string.
The following are examples of invalid literals:
1 23
Spaces are not permitted in number literals.
$10.99
Periods are not permitted in an unquoted character string, and the dollar sign is not permitted in a number literal.
‘John’s toy boat’
‘John’ is a valid character string, but the rest of the line is invalid.

Callback Events

A “callback event” (or simply an “event”) is an interaction, between the end-user and the application interface, that causes a FORM INPUT or MENU INPUT command to terminate, and control to pass the next command in the executing program.
There are two types of potential events that can occur: object dependent and object independent.

The available set of object dependent event types are:

In ZimIDE, the CallBackEvents set of properties enables the selection of event types that can be made active for a particular object.
The dialog presents only those event types which the object type can support.
Note that menu items that do not have any child menu items support only the Click event, and they are always active for that event type.
When an event is made active for an object, the occurrence of that event causes either a FORM INPUT or a MENU INPUT command to terminate and execution control to pass to the next command in the executing program. In addition, the Event Vector Event is populated with information describing the event (cf. Event Vector).
The event properties Name, Type, and Tag are of particular importance for program execution control.

The Purpose of Masking Patterns

Masking patterns are used to format data values in a manner appropriate to the type of information they represent.

For example, in Zim, dates are stored as a special type of numerical value, in which the first four digits represent the year, the next two represent the month and the last two stand for the day.

As such, the date June 28, 2014 is stored numerically as 20140628. This allows for mathematical operations to be performed on dates, but this format is not intuitive for presentation.

By using a masking pattern, such as “DD/MM/YYYY”, this date value will now be presented as the string “28/06/2014”, which is instantly recognized as a date.

The same masking pattern is also used to format the input of data into a date entry field. Instead of typing 20140628, the end-user can type 28062014, because the separator character / is only presented between the year, month and day values, but is not actually part of the date value itself.

The same principle can be applied to separator characters in currency values, postal codes, phone numbers, etc.

Situations in Which Masking Patterns Are Used

Zim offers the possibility of applying data masking patterns in different situations, each with a specific set of fixed and masking characters, as summarized in the table below (follow the links in the first columns for more information):

Masking Characters According to Data Types

The set of available masking characters is different according to the Data Type property (DT) of the entity set field or the entry field.

The following sections describe the available masking characters for each data type:

Alphanumeric Masking

Alphanumeric masking is used to format generic text data. It is particularly useful when data is entered in shortened form but displayed in full form.

In the output value, each question mark is replaced by one character from the current value of the report item, in order from left to right.

When no more characters remain in the value, any remaining question marks become spaces.

Alphanumeric Masking Characters

Examples

Field Mask      MASK      $mask

Leading or trailing spaces are indicated by / in the Output column.

Data Mask

Note:

If the CM (compress status) attribute of a form field is N, the value of the form field is the same as the displayed data. Otherwise, the value of the form field is the same as the input data vlue.

lf the mask pattern is shorter than the field length, then the mask is assumed to contain ? characters in the missing positions (See the last example above).

Non-Digit Masking

Non-digit mask patterns are nearly identical to alphanumeric ones, with the exception that digits (0, 1, …, 9) are not accepted as valid input.

Date Masking

Date masks are composed of three types of character groups, representing the year, month and day, which can be combined in any order.

Between each group there may be an optional fixed separator character, such as /, –, ., or blank space, which appear in the display or output as is.

For date entry fields, the default masking pattern is MM/DD/YY.

Date Masking Characters

Examples

Field Mask      MASK      $mask

Leading or trailing spaces are indicated by / in the Output column.

Data Mask

Numeric Masking

When the data item contains decimals, the decimal point in the mask pattern is aligned with the decimal point in the value, and digit substitutions are made from right to left for the mask characters to the left of the decimal point, and from left to right for the mask characters to the right of the decimal point.

A series of 9s can therefore be used to force the printing of non-significant zeros to the right of the decimal point (in dollar values, for example). A 9 would also be used to force the printing of leading zeros in serial numbers: for example, 009876.

Any report item whose current value is too large to fit in the specified mask pattern (including the sign output, if applicable) causes the overflow characters (asterisks) to be displayed.

• the currency placeholder ($) and sign placeholders: plus (+), minus (–), left and right parentheses (( and )), and the special character strings CR and DB

The currency placeholder inserts the applicable currency symbol into the output value.

Sign placeholders reflect the sign of the number (positive or negative) in the output value. The left parenthesis can be used only on the left-hand side of the mask pattern. The CR, DB and left and right parenthesis can be used only on the right-hand side of the mask pattern. The plus and minus signs can be used on either side of the mask pattern.

The plus and minus signs, left parenthesis, and the dollar sign can be used as float characters. A single plus, minus, dollar sign, or left parenthesis can also “float” ahead of a series of other floating characters.

• fixed text characters

Typically, in the output value, fixed text characters (e.g., commas) appear as is, provided that there are digits remaining to be substituted into the mask or that the mask character 9 forces the output of zeros.

Numeric Masking Characters

Examples

Field Mask      MASK      $mask

Leading or trailing spaces are indicated by / in the Output column.

Data Mask

Opens a window for use in subsequent window-handling commands.

Syntax

WINDOW OPEN [window] [AT position] [SIZE winsize] [FOR form] [IN parent]

Parameters

Comments

WINDOW OPEN opens the specified window and establishes its initial position and its physical and logical dimensions.

The window being OPENed becomes the current window, but it does not automatically appear on the screen. To appear on the screen, the window must be activated either explicitly by a WINDOW ACTIVATE command, or implicitly by an input request (e.g., FORM INPUT, INPUT, MENU INPUT).

WINDOW OPEN makes the window available for output. Forms can be open and displayed in the window, and output from commands such as REPORT FROM, LIST, OUTPUT, and so on, can be sent to the window. The output appears only when the window is activated.

If the AT clause is omitted, the window appears at the position defined for it in the Object Dictionary.

A window’s position is always relative to its physical parent. The physical parent of a clipped window is another window (parentwin). The physical parent of a pop-up window is the terminal.

If the arguments to the AT clause are such that the window opens out of bounds, the position is adjusted automatically so that the window remains entirely within the parent’s boundaries.

If the SIZE clause is omitted, the dimensions of the window’s client area are determined from the window’s definition in the Object Dictionary.

If either dimension in a SIZE clause is negative, the window is sized to maximize the associated dimension within parentwin with respect to the specified row and col position.

If the FOR clause is omitted, the logical dimensions of the window are determined from the window’s definition in the Object Dictionary.

If the IN clause is omitted, the newly opened window automatically becomes a “child” of the application window (BACKSCREEN).

The IN clause tells Zim to clip the window being opened to the parent, provided that the child window has the Clipped to Parent attribute set. Otherwise, the child window will be opened as usual.

WINDOW OPEN [re]sets the fields of the ThisWindow system variable.

See Also

$iswinopen

ThisWindow

WINDOW ACTIVATE

WINDOW CLEAR

WINDOW CLOSE

WINDOW DEACTIVATE

WINDOW DISPLAY

WINDOW SCROLL

WINDOW SET

WINDOW SIZE

Enables conditional execution of commands.

Syntax

CASE

WHEN expression

commands1

[OTHERWISE

commands2]

ENDCASE

Parameters

Comments

A CASE command must always have a corresponding ENDCASE. Any number of WHEN clauses can appear between CASE and ENDCASE.

The WHEN phrases between CASE and ENDCASE are evaluated in order. Execution control transfers to the commands associated with the first WHEN clause whose expression is determined to be logically true. If none of the WHEN phrases contain an expression that evaluates to “true”, the commands associated with OTHERWISE (if used) are executed. Execution then resumes at the first command following ENDCASE.

If a WHEN expression includes fields from the current set, then the expression uses the values found in the current member of the current set.

If a BYE, RETURN, STOP, or TRANSFORM command exits a procedure in the middle of a CASE structure, the “open” CASE command is automatically closed. Also, if the end of the current procedure is reached before a necessary ENDCASE is encountered, the “open” CASE command is closed.

If the ENDCASE is missing, all subsequent commands in the current procedure are treated as part of the CASE structure.

Example

If the value for salary is neither less than 20,000, nor between 20,00 and 30,000, the first and second set of commands are skipped, and the third set of commands executed.

case

when salary < 20000

… first set of commands …

when Salary between 20000 and 20000

… second set of commands …

otherwise

… third set of commands …

endcase

The following program fragment illustrates how WHEN conditions in a CASE command can handle an application user’s choice of accelerator keys in an application. Depending on the key pressed by the application user, a particular procedure is executed.

form display input

case

when Event.EventName = “F3”

return

when Event.EventName = “F1”

AddNewRecord ()

when Event.EventName = “F2”

ChangeRecord ()

when Event.EventName = “F4”

DeleteRecord()

otherwise

GiveHelp ()

endcase

Opens a form or display in the current window.

Syntax

FORM OPEN [object][ NOCLEAR][ NOGUIUSE]

Parameters

Comments

The FORM OPEN command initializes a form or display for use.
The form or display is displayed using the FORM DISPLAY command, and input is requested using the FORM INPUT command.

The form or display specified in a FORM OPEN command remains the current form in its window until a FORM OPEN, FORM CLOSE, or WINDOW CLOSE command is executed.
Each window has its own current form.

When a FORM OPEN command is executed, all ,em>form field attributes are reset to their defined values.
An exception is the field’s value, which is not reset if the NOCLEAR option is used.

The FORM OPEN command also establishes a form for use as an in-memory EntitySet.
When treated as an EntitySet, a standalone form has only one record.
The forms in a display have as many records as there are instances of a particular form in the display.

Examples

form open dAddEmps

Opens a display and resets all constituent form fields to their default values.

form open fAddEmps
form display input
form close
:
form open fAddDepts
form display
close
:
form open fAddEmps noclear
form display

Opens a form and resets its field values, then displays the form and requests user input. Next, a second form is opened and displayed.
Finally, the first form is opened again, and the field values input earlier are re-displayed (because the NOCLEAR option was specified).

form open ($ concat(" fContracts", ContractType))

Opens a certain form dynamically by type.

See Also

FORM CLEAR

FORM CLOSE

FORM SET

Displays some or all of the form fields of the currently open form or display in the current window.

Syntax

FORM DISPLAY [ option ] [ object ]

Parameters

Comments

The current window must be activated (WINDOW ACTIVATE) for the displayed objects to be visible.
FORM DISPLAY displays form fields with values as they exist at the time the command is executed. If the application program changes the value of a field, the field must be re-displayed if the application user is to see the change.
A masked field that has no data value is displayed without the mask if the field is unavailable to the application user (i.e., protected or guarded). The mask of such a field is shown or suppressed when its availability changes (as a result of the FORM SET command).

Example

form display fGrandTot fInvItem.InvItemTot

Redisplays all fields of one form, and one field of another form.

form display input bell (2,,5)

Sounds the bell while re-displaying all form fields in the fifth instance of form number 2.
Name of the application directory in which the specified object can exist. If the dirname is omitted, the object can be created in any number of directories.

See Also

FORM CLEAR

FORM INPUT

FORM OPEN

FORM REPORT

FORM SCROLL

FORM SET