[asterisk-dev] 10787: Impossible to make optional macro arguments in AEL

[Philipp Kempgen]

https://issues.asterisk.org/view.php?id=10787

May I suggest to reopen that issue?
Here's an example: I have a macro
macro sip-remove-header( sipremoveheader_arg ) {
    ...
}
which calls SIPRemoveHeader() if that application exists or else
it emulates the behavior.

SIPRemoveHeader() can be called with or without an argument --
or more precisely: with an empty string as an argument.

murf: You name it: "everything is strings"
IMHO an empty string is a perfectly valid argument.
(I'm fine with implementing that as a default value for the argument
but default values are not even necessary.)

However the AEL parser does not let me call
&sip-remove-header();

("pbx_ael.c:... check_pval_item: Error: file ..., line ...:
The macro call to sip-remove-header has 0 arguments, but the macro
definition has 1 arguments")

My workaround: Trick the AEL parser by passing an empty argument:
&sip-remove-header(${});

The point is that "everything is strings" and a zero-length string
is still a string.
(IMHO strings should have to be quoted in the first place but that's
a different story.)

If there are objections then at least this e-mail serves as a
"how to pass empty/optional arguments in AEL". :-)


    Philipp Kempgen
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