ST COMPUTE EXPRESSIONS
ST COMPUTE EXPRESSIONS ( {* ;} object {; startSel {; endSel}} )
| Parameter | Type | Description | |
|---|---|---|---|
| * | Operator | → | If specified, object is an object name (string) If omitted, object is a field or variable |
| object | any | → | Object name (if * is specified) or Field or variable (if * is omitted) |
| startSel | Integer | → | Start of selection |
| endSel | Integer | → | End of selection |
This command is not thread-safe, it cannot be used in preemptive code.
Description
The ST COMPUTE EXPRESSIONS command updates the dynamic 4D expressions found in the multi-style or 4D Write Pro field or variable designated by the object parameter.
For more information about 4D expressions used in multi-style text or 4D Write Pro areas, refer to the description of the ST INSERT EXPRESSION command.
The command re-evaluates the result of expressions found in the object based on the current context and displays the result obtained. For example, if the expression inserted is the time, the value will be modified each time the ST COMPUTE EXPRESSIONS command is called. Expressions are also computed:
- when they are inserted
- when the object is loaded
- when they are "frozen" using the ST FREEZE EXPRESSIONS command, if the second * parameter is passed.
ST COMPUTE EXPRESSIONS does not modify styled text (containing span tags) but only plain text displayed in object. The values computed are not stored in the styled text, only their reference is stored there.
Passing the optional * parameter indicates that the object parameter is an object name (string). If you do not pass this parameter, it indicates that the object parameter is a field or variable. In this case, you pass a field or variable reference instead of a string.
It is not necessary for the object to have the focus. However, if the object designates a multi-style text area, it must be included in a form or else the ST COMPUTE EXPRESSIONS command has no effect.
Note: If the object designates a 4D Write Pro document, it will be computed by the command even if it is not opened in a form object (see also Picture expressions).
The optional startSel and endSel parameters designate a selection of text in object. The startSel and endSel values express a plain text selection, without taking into account any style tags or references that may be present. Note that a reference is equivalent to a single character.
- If you pass startSel and endSel, ST COMPUTE EXPRESSIONS only updates the expressions located within this selection.
- If you only pass startSel or if the value of endSelis greater than the total number of characters in object, all the expressions between startSel and the end of the text are computed.
- If you omit startSel and endSel, all the expressions included in the user selection of the object are computed.
4D provides predefined constants so that you can designate the selection limits automatically in the startSel and endSel parameters. These constants are found in the "Multistyle Text" theme:
| Constant | Type | Value | Comment |
|---|---|---|---|
| ST End highlight | Longint | -1001 | Designates last character of current text selection in object (*) |
| ST End text | Longint | 0 | Designates last character of text contained in object |
| ST Start highlight | Longint | -1000 | Designates first character of current text selection in object (*) |
| ST Start text | Longint | 1 | Designates first character of text contained in object |
(*) You must pass an object name in object to be able to use this constant. If you pass a reference to a field or variable, the command is applied to all the text of the object.
Note: If startSel is greater than endSel (except when endSel is 0), the command does nothing and the OK variable is set to 0.
Example
You want to update the references included in the selection of text:
ST COMPUTE EXPRESSIONS(*;"myText";ST Start highlight;ST End highlight)