On 10.03.2018 20:33, MG wrote:
Hi Jochen,
I was not aware that Groovy is so sophisticated in its expression
analysis, that it actually uses intersection types
you actually do not have much of a choice. It is an AST-only
representation only though.
[...]
3. It would, on the other hand, allow to introduce var support not
based on var === def to dynamic Groovy later on, without breaking
backwards compatibility (because var x = new Foo(); x = 123
suddenly does not work any more)
what exactly is the advantage of not having var === def? Only to
disallow the reassignment in some cases at runtime? I do not see much
gain in that actually
Just food for thought - I personally would prefer to see the "90%
solution" I talked about in an earlier post for dynamic Groovy:
Support var x = RHS -> typeof(RHS) x = RHS for simple cases, such as:
var x = new Foo(...)
var x = (Foo) ...
var x = foo(...) // use the explicit return type of method foo(), CTE on
return type == def ("'var' not supported for 'def' as return type - use
Object as return type of method or define variable using 'def'.")
throw CTE in all other cases (least surprise - "'Type for variable
defined with 'var' cannot be deduced in dynamic Groovy. Annotate the
method/class with @CompileStatic to switch to static compilation, or
replace 'var' with 'def'."
there is almost no expressions consisting of multiple expression, that
we can tell the type of in dynamic mode. Even something simple as 1+1
can in theory return a ComplexNumber suddenly.
[...]
From the view of my framework code that goes even more so for the
related case of final x = RHS -> final typeof(RHS) x = RHS I therefore
keep going on about - if dynamic Groovy does not pick up the RHS type
for final, I need to keep my current code, or force framework users to
use @CompileStatic on all Table derived classes, if they want to define
table columns in the most elegant and concise way... :-)
for "final x = ..." the exact type of x is in dynamic mode actually
totally not relevant. There is no reassignment, so that problem is out
here. But if we forget about that, then there is no difference between
"final x" and "def x". I know cases where it could make a difference,
but they do not exist in Groovy yet. so what exactly is final x supposed
to do different than def x besides the reassignment?
bye Jochen
