Hi Jochen,
On 25.08.2017 10:05, Jochen Theodorou wrote:
On 23.08.2017 00:52, MG wrote:
Hi Paul,
On 21.08.2017 04:30, Paul King wrote:
Introduce a "var" (o.s.) keyword that allows deduction of type
through assignment:
var device = new PrinterDevice(...) // device variable will have
type PrinterDevice without the need to explictely state that
Rationale: This is a well known feature of other languages, that
reduces the need to explictely define the type of variables.
How is this different to the current type inferencing?
The variable/field will have the type of the initally assigned value
(instead of Object when using def), therefore one cannot accidentially
assign any other type to it.
Didn't see a further comment on this so... If you have the static
compilation mode we use flow typing to determine the type of the
variables. That means:
def x = ""
will make x have the type compile time type String, so that x.foo()
will be marked as compilation error. Flow typing means you can do this:
def x = ""
x = 1
Flow typing is cool, and I would gather much harder to implement than a
"var" keyword (btw, I actually just used the name used by C#, even
though picking a different name might be a better choice, to avoid
confusion with e.g. Javascript).
I would however argue that in the majority of cases one will not want to
assign an integer value to a "String variable", but will want to keep
the type assigned at declaration time, so a var keyword to me is an
orthogonal feature to flow typing.
without getting an error. Basically you loose compile time checks on
assignment and gain more flexibility on the usage of the variable. But
since you seem to want to make everything final if possible, that
should not bother you too much.
Emphasis on "if possible"... :-)
Var would be for the remaining cases where variable reassignment is the
most sensible approach.
The bottom line is: var kind of the default in static compilation mode
see under "orthogonal feature" above; var would work in dynamically as
well as statically compiled code, so it is also orthogonal in that sense.
Cheers,
Markus
