The concept of which metaops can apply to which other ops is looking
pretty clear.
The goal, as I understand it from Larry, is that while in general,
metaops should be allowed, we want to disallow them where they either
make no sense, or are very unlikely to be what the programmer thought
they were doing.
In addition, it seems to me that since metaops should be applicable to
user created ops, the particular tests the parser performs must be
well defined because users will be annotating their operators to get
them to have the right metaop applicability.
I propose the following:
Rop infix --> infix
Xop infix --> infix
op<< prefix --> prefix
>>op postfix --> postfix
>>op<< infix --> infix
- the inner op should be "value" like, that is things
like ==> and .= and ^ff^ don't ever really make sense here
- these should test for :value
[op] infix --> prefix
op= infix --> infix
- the inner op needs to be associative, and needs to produce a value
of similar type to its arguments
- these should test for :iso
- [op] has an explicit provision for chained operators
- so [op] should support :assoc(chain) if the op is :value
!op infix --> infix
- the inner op must return a value that makes sense when used in a
boolean context, and hence when negated
- this should test for :bool
The current levels would then have:
%methodcall
%autoincrement :value
%exponentiation :value :iso
%symbolic_unary :value
%multiplicative :value :iso
%additive :value :iso
%replication :value :iso
%concatenation :value :iso
%junctive_and :value :iso
%junctive_or :value :iso
%named_unary :value
%nonchaining :value
%chaining :value :bool
%tight_and :value :iso
%tight_or :value :iso
%conditional
%item_assignment
%loose_unary :value
%comma
%list_infix :value :iso
%list_assignment
%list_prefix
%loose_and :value :iso
%loose_or :value :iso
%sequencer
Two exceptions to these lists:
sym<,> gets :value and :iso
sym<%> gets :bool as well
I'm not so happy with these names, :boolish? :simple? I just don't
know...
This does explicitly remove a few classes of operator from being used
in hyper, reverse and cross: Such things as the sequencer ops,
assignment, and method call. Testing with the current form of STD.pm
(r25127), not all of those things parse anyway.
I almost have a patch against STD.pm ready to go that implements this
and passes teststd... What do you think? Post it here? Check it in?
This is a goofy idea, drop it?
- MtnViewMark
