Error Handling

When an error occurs during the execution of a GISDK macro, Caliper Script normally displays a message with reference information and aborts execution of the GISDK macro in which it occurs and any calling GISDK macro. The reference information has three parts:

• the name of the resource file in which the error occurred

• the line number at which the error occurred

• an error code, as shown in the table below

The message gives you the opportunity to launch the GISDK Debugger, if appropriate. Execution of the resource file is set back to just before the error occurred. For more information, see Using the GISDK Debugger.

Caliper Script provides four statements for customized error and exception handling, with these formats:

on exceptions goto label

on exceptions default

on exceptions do

<statements go here>

goto label

end

on exceptions do

<statements go here>

Return()

end

Once error handling is enabled for an exception type, the error handler remains in place throughout the GISDK macro or dialog box item, until it is replaced by another error handler, or canceled by the "on exceptions default" statement.

As of Version 2018, if a macro has no error handler, but a calling macro does, then that error handler will capture the error.

Here is an example:

on notfound do
ShowMessage("There is no States layer in this map!")
goto no_states
end
SetLayer("States") // If this fails, the error handler runs
SetBorderColor(, clr1) // A notfound here will use the same error handler!
SetFillColor(, clr2) // Same here
no_states:
on notfound default // Cancels the special error handling

Normally each handler will be for one exception:

on error do
Return()
end
on notfound do
Return()
end

If you have two handlers that do the same thing, such as these examples, you can have one handler for a list of exceptions:

on error, notfound do
Return()
end

The exception types are: