Am 21.03.2018 um 09:27 schrieb Cédric Champeau:
[...]
In any case, I was doubtful as you are here before actually using it in
Kotlin. After a few weeks, it became clear to me this syntax was both
more concise and more self-explanatory.
For me {} was always very clear, for {} starts a new scope, it is a
block, that can return something. I did never even once think about
these as expressions. That is why I really not often speak about closure
expressions, but about attached and open blocks or Closure. And in that
matter:
double x
double y
double surface(double x, double y) = x * y
I find it very unclear if the x is the field/property x or the method
parameter. That is because normally = does not create a new scope. And
especially normally = does not allow referencing variables from the left
side declaration. For example:
class X {
def foo = 1
def bar() {
def foo = foo*2
}}
This is allowed in Groovy and Java, because the semantics are very
clear. Since = does not do a forward declaration the local variable foo
is not defined on the RHS. Thus the foo on the RHS can only mean the
property/field.
class X {
def foo = 1
def bar(foo) {
def foo = foo*2
}}
This is not allows, because the block already declares a foo and another
local variable of the name foo is not allowed
class X {
def foo = 1
def bar(foo) {
def bar = foo*2
}}
This is allowed and again the semantics are clear, because the parameter
is a local scope that shadows the class scope, thus in the declaration
of bar the foo in RHS means the foo from the method parameter.
double surface(double x, double y) = x * y
breaks with the former declaration and scoping logic. You can try rescue
this by saying the = in the method declaration has nothing to do with
the = in a declaration or assignment otherwise. But if I always have to
do the expansion to the other version to understand what happens, then
it is not easier for me.
On top of that I am a real bad fit for this style, because except for
demo purposes I rarely write methods that contains only a single line of
code. Maybe you could show real world examples that show the real
coolness of this?
bye Jochen
