1. routine_id scope
- Posted by xecronix Oct 20, 2015
- 1580 views
Forked from Re: Is there a good Windows or cross-platform Euphoria IDE?
This also confuses me:
public function Icallback( sequence name, atom rid = routine_id(name) ) return call_back( rid ) end function
From your example, it looks like you can not only do an assignment to a non-constant value, but you can pass one of the parameter values.
Where is this in the manual defined? The manual says:
PROCDECLARE ==: [SCOPETYPE] 'procedure' IDENTIFIER '(' [PARMLIST] ')' [STMTBLK] 'end' 'procedure'
PARMLIST ==: PARAMETER [',' PARMLIST]
PARAMETER ==: DATATYPE IDENTIFER
Maybe it's just that my Google-fu skills are lacking, but I can't find any mention default parameter values in the on-line manual.
There are some examples where they are used, but that's not quite the same.
- David
I found some discussion on scope for routine_id but nothing that calls attention to Greg's trick.
2. Re: routine_id scope
- Posted by ghaberek (admin) Oct 20, 2015
- 1564 views
Where is this in the manual defined?
It's in 4.2 Declarations, under 4.2.1.1 procedures.
For a number of procedures or functions--see below--some parameters may have the same value in many cases. The most expected value for any parameter may be given a default value. Omitting the value of such a parameter on a given call will cause its default value to be passed.
procedure foo(sequence s, integer n=1) ? n + length(s) end procedure foo("abc") -- prints out 4 = 3 + 1. n was not specified, so was set to 1. foo("abc", 3) -- prints out 6 = 3 + 3
(emphasis mine)
-Greg
3. Re: routine_id scope
- Posted by ghaberek (admin) Oct 20, 2015
- 1567 views
I found some discussion on scope for routine_id but nothing that calls attention to Greg's trick.
It was in this thread: init.e - standard library candidate.
However, routine_id() is unique in that, like repeat() or it(), routine_id() relies on scoping to interpret the value of its parameter. So, what should routine_id() do? Should it use the scope where the routine is called, or the scope where the routine is defined? This only applies to routine_id(), since no other routine cares about scope in the same way when it is called.
-Greg
4. Re: routine_id scope
- Posted by dcuny Oct 20, 2015
- 1559 views
It's in 4.2 Declarations, under 4.2.1.1 procedures.
Yep. 
Could this be given a heading? It's easy to miss, even when looking for it. It's not in the index, and it's not in any list. I literally skipped over it multiple times, even knowing what I was looking for.
It's a great feature.
Thanks!
- David
