Handlers (AS Language)

Inside Macintosh: AppleScript Language Guide / Part 3 - Appendixes: Appendix A - The Language at a Glance

Handlers
Handlers are collections of statements that are executed in response to commands or error messages. Table A-6 summarizes handler definitions
and subroutine calls.
Handler definitions and calls
Handler Syntax
Subroutine definition (labeled parameters) ( on | to ) subroutineName å
[ of | in directParameterVariable ] å
[ subroutineParamLabel paramVariable ] ... å
[ given label:paramVariable [, label:paramVariable ]...]
[ global variable [, variable ]...]
[ local variable [, variable ]...]
[ statement ]...
end [ subroutineName ]
Subroutine call (labeled parameters) subroutineName å
[ ( of | in ) directParameter ] å
[ subroutineParamLabel parameterValue ] å
| [ with labelForTrueParam [, labelForTrueParam ]... å
[( and | or | , ) labelForTrueParam ] ] å
| [ without labelForFalseParam [, labelForFalseParam ]... å
[( and | or | , ) labelForFalseParam ] ] å
| [ given label:parameterValue å
[, label:parameterValue ]...] ] ...
Subroutine definition (positional parameters) ( on | to ) subroutineName ( [ paramVariable [, paramVariable ]...] )
[ global variable [, variable ]...]
[ local variable [, variable ]...]
[ statement ]...
end [ subroutineName ]
Subroutine call (positional parameters) subroutineName ( [ parameterValue [, parameterValue ]...] )
Return statement return expression
Command handler definition ( on | to ) commandName å
[ [ of ] directParameterVariable ] å
[ [ given ] label:paramVariable [, label:paramVariable ]...]
[ global variable [, variable ]...]
[ local variable [, variable ]...]
[ statement ]...
end [ commandName ]

Handler definitions and calls
Handler	Syntax
Subroutine definition (labeled parameters)	( on \| to ) subroutineName å [ of \| in directParameterVariable ] å [ subroutineParamLabel paramVariable ] ... å [ given label:paramVariable [, label:paramVariable ]...] [ global variable [, variable ]...] [ local variable [, variable ]...] [ statement ]... end [ subroutineName ]
Subroutine call (labeled parameters)	subroutineName å [ ( of \| in ) directParameter ] å [ subroutineParamLabel parameterValue ] å \| [ with labelForTrueParam [, labelForTrueParam ]... å [( and \| or \| , ) labelForTrueParam ] ] å \| [ without labelForFalseParam [, labelForFalseParam ]... å [( and \| or \| , ) labelForFalseParam ] ] å \| [ given label:parameterValue å [, label:parameterValue ]...] ] ...
Subroutine definition (positional parameters)	( on \| to ) subroutineName ( [ paramVariable [, paramVariable ]...] ) [ global variable [, variable ]...] [ local variable [, variable ]...] [ statement ]... end [ subroutineName ]
Subroutine call (positional parameters)	subroutineName ( [ parameterValue [, parameterValue ]...] )
Return statement	return expression
Command handler definition	( on \| to ) commandName å [ [ of ] directParameterVariable ] å [ [ given ] label:paramVariable [, label:paramVariable ]...] [ global variable [, variable ]...] [ local variable [, variable ]...] [ statement ]... end [ commandName ]