On 30.10.2016 11:07, Daniel.Sun wrote:
Hi Paolo,
There are some limitations when we use antlr to define grammar, so the
backticks are used to distinguish with other operators.
I saw an answer from Jochen(shown as follow), so I tryied to add this
experimental feature
"We always wanted the ability to define an operator through the user in
Groovy, but so far we haven't gotten around the problems that come along
with that."
http://stackoverflow.com/questions/6485861/is-it-possible-to-define-a-new-operator-in-groovy/10848093#10848093
I actually gave up on custom operators for a bit.
In Scala you have a natural mapping of "a + b" to a."+"(b). But in
Groovy that would be a(+).b. That means binary expressions and command
expressions follow different patterns. That means in a+b+c we do not
naturally get (a+b)+c, we get a(+).b(+).c. This is what makes you
require special characters to distinguish operators and command
expressions in the usage of those
And if you change precedence rules like you described... a + b + c is
(a+b)+c while a + b "`x`" c would become a+(b "`x`" c) instead.
But to develop the idea... how about saying that everything between dot
and an identifier is an operator? So a .x c would be a.x(c).. well that
looks obvious, but a .>? c becomes a.">?"(c). This kind of logic would
reduce the need for special characters and be in line with existing
syntax. And at the same time precedence rule would be clear. a + b .>? c
would be a+(b.">?"(c)) and a .>? b +c would become (a.">?"(b))+c
bye Jochen
