Page 433 - Asterisk™: The Future of Telephony

The calling extension, context, and priority are stored in ${MACRO_EXTEN}, ${MACRO_CON
TEXT}, and ${MACRO_PRIORITY}, respectively. Arguments arg1, arg2, etc. become $
{ARG1}, ${ARG2}, etc. in the macro context.
Macro() exits abnormally if any step in the macro exited abnormally or indicated a
hangup. If ${MACRO_OFFSET} is set at termination, this application will attempt to con-
tinue at priority MACRO_OFFSET+n+1 if such a step exists, and at n+1 otherwise. (In both
cases, n stands for the current priority.)
If you call the Goto() application inside of the macro to specify a context outside of the
currently executing macro, the macro will terminate and control will go to the desti-
nation of the Goto().
; define a macro to count down from the specified value
[macro-countdown]
exten => s,1,Set(COUNT=${ARG1})
exten => s,2,While($[ ${COUNT} > 0])
exten => s,3,SayNumber(${COUNT})
exten => s,4,Set(COUNT=$[ ${COUNT} - 1 ])
exten => s,5,EndWhile()

; call our macro with two different values
[example]
exten => 123,1,Macro(countdown,10)
exten => 124,1,Macro(countdown,5)

While a macro is being executed, it becomes the current context. This
means that if a hangup occurs, for instance, the macro will be searched
for an h extension, not the context from which the macro was called.
So, make sure to define all appropriate extensions in your macro (you
can use catch in AEL).

Because of the way Macro() is implemented (it executes the priorities
contained within it via sub-engine), and a fixed per-thread memory
stack allowance, macros are limited to seven levels of nesting (macro
calling macro calling macro, etc.); It may be possible that stack-intensive
applications in deeply nested macros could cause Asterisk to crash ear-
lier than this limit.

See Also
MacroExit(), Goto(), Gosub(), Chapter 6

MacroExclusive() Runs a macro, exclusive of any other channel
MacroExclusive(macroname[,arguments])

MacroExclusive() | 405