Re: @Bill: 'alius' question

   From: "Ger Hobbelt" <[email protected]>

   QUICKREF says:

   alius                             - if the last bracket-group succeeded, ALIUS
				       skips to end of {} block (a skip, not a
				       FAIL); if the prior group FAILed,
				       ALIUS does nothing.  Thus, ALIUS is both
				       an ELSE clause and a CASE statement.

How about (for the QUICKREF):

   alius -       if the last bracket-group succeeded, 
   	 	 ALIUS skips to the "}" end of
	 	 THE SMALLEST {} block ENCLOSING THE ALIUS <<<--- NEW!! 
		 (a skip, not a FAIL);
		 if the prior group FAILed,
		 ALIUS does nothing.  Thus,
		 ALIUS is both an ELSE clause
		 and a CASE statement.
    


[[ reformatting to make it easier for those of us with reading glasses ]]

   Given code like this:

   {
	{
		a
    	}
    	alius
    	{
		b
    	}
    	c
   }
   d

   the question is:

   given a successful 'a', alius will skip. Should it skip to 'c' or 'd'?

If codeblock "a" exits with a FAILure (either a CLASSIFY, an EVAL, or
an explicit FAIL) then the ALIUS statement should allow codeblock "b"
and then codeblock "c" to execute.

If codeblock "a" exits successfully (that is, not a FAILure) then the
alius statement will skip to the smallest "}" that encloses the ALIUS,
which in this case is the "}" before "d".

This is so you can do things like the if-then-else and CASE statements
by just stacking clauses:

   {
	{
		match "blahblahblah"
		do this and that....
    	}
	alius
	{
		match "boogaboogabooga"
		do that and those...
	}
	alius
	{
		match "drumdrum"
		do those and them...
	}
	alius
	{
		match "redrum"
		do them and these...
	}
	.... repeat as desired...
   }

Basically, each ALIUS can be considered a marker to "try this
alternative next ONLY if everything above this failed".


   To me, the definition in QUICKREF is a little ambiguous. Some existing
   code (mail*.crm) suggests 'skip to c' i.e. 'skip the subsequent
   curly-braces block', but since I have been fiddling with the compiler
   to make it validate scripts in more detail like a good compiler
   should, I want to be absolutely sure what the original intent was:

   skip to c or d?

d.

Does the above change to the QUICKREF make it clearer?

     - Bill Yerazunis

     

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