Placeholder Concept

At each location in the configuration dialog at which variables or text are entered, a placeholder can be set in place of the respective variable or text. This makes sense if the visualization object is not to be used directly in the program, but is created to be inserted in other visualization objects as an "instance". When configuring such an Instance, the placeholders can be replaced with variable names or with text (see „Configuring an inserted visualization", there you also find an example for using placeholders).

Any string enclosed in two dollar signs ($) is a valid placeholder (e.g. $variable1$, variable$x$). For each placeholder a „value group" can be defined as an input specification in the 'Placeholder list' dialog (called from 'Extras' 'Placeholder list'). With one of these values you can replace the placeholder when configuring an instance of the visualization object. A placeholder list will be available in the instance to do this replacements

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'Extras' 'List of Placeholders...'

• primarily you use the list when configuring a visualization object, which later should be inserted, which means instanced, in other visualization(s). For this reason you will use placeholders instead of or additionally to variables and strings in the configuration dialogs. You can open the dialog 'Placeholders' by the command 'List of Placeholders' in the 'Extras' menu or in the context menu. The list shows three columns:
  

Placeholder list for input of possible replacements for the placeholders

• Column Placeholder will list all placeholders, which are currently used in the configuration of the visualization object. Column Element number shows the elements which contain a placeholder. In column Replacements you can enter one or several strings (text, variable, expression) which you want to get available later when replacing a placeholder during the configuration of an instance of the visualization object. The elements of the selection must be entered separated by commas. If no or an impossible replacement string is specified, then the placeholder can be replaced with any desired text later during the configuration of the visualization's reference.
• later you use the list of placeholders when configuring an instance of the above mentioned visualization object, that means after this object has been inserted (as a 'reference') in another visualization by the command 'Insert' 'Visualization'. For this purpose do the following to open the dialog: Select the inserted visualization, execute command 'Extras' 'Configure' and press button 'Placeholders' in Category 'Visualization'. In this case the dialog will only contain two columns:
  

List of placeholders for replacing a placeholder in a visualization instance

• Column Placeholder – like described above – shows all placeholders which have been defined for the primary visualization object. If additionally a selection of possible replacements had been defined, this list will now be available in column 'Replacement'. Select one of the entries to replace the placeholder in the present instance. If no replacements have been pre-defined then you can manually enter an expression or variable. For this purpose perform a mouse-click on the field in column Replacement to open an editor field.