« Return to Thread: idea: val x, y {... x = ... y = ...}

Re: idea: val x, y {... x = ... y = ...}

by Rob Dickens-2 :: Rate this Message:

Okay, here's something more realistic - a method that gets called periodically, in this case to make something 'look' at the next point in space:

// scala version

def complete(context: Context): Boolean = {

val (x, y, z) = {

val progress = {

val elapsedSecs = (System.currentTimeMillis - startMillis/1000).toInt

if (elapsedSecs > flightSecs) return true

elapsedSecs.toDouble/flightSecs

}

val (_x, _y) = {

val d = range*progress

(frX + (d*kX).toInt, frY + (d*kY).toInt)

}

val _z = (4*range*(progress - progress*progress)).toInt

(_x, _y, _z)

}

context.driver.look(separation, x, y, z)

false

}

// scalax version

def complete(context: Context): Boolean = {

val x, y, z {

val progress = {

val elapsedSecs = (System.currentTimeMillis - startMillis/1000).toInt

if (elapsedSecs > flightSecs) return true

elapsedSecs.toDouble/flightSecs

} {

val d = range*progress

x = frX + (d*kX).toInt

y = frY + (d*kY).toInt

}

z = (4*range*(progress - progress*progress)).toInt

}

context.driver.look(separation, x, y, z)

false

}

2009/5/21 Ricky Clarkson <ricky.clarkson@...>

point {

val a = 1 + 2
val b = 3 + 4
(a + 1, a + b, a - b)
}

I know it looks like I'm just being picky, but I'm encouraging you to
give a use case. Perhaps this is one:

val (x, y, z) = {
val a = 1 + 2

val _x = a + 5
val _y = _x + 3
val _z = _y * 4
(_x, _y, _z)

}

2009/5/21 Rob Dickens <arctic.bob@...>:
> So maybe I should have written,
> def scalaVersion() {
>   val (x, y, z) = {
>    val a = 1 + 2
>    val _x = a + 1
>    val b = 3 + 4
>    val _y = a + b
>    val _z = a - b
>    (_x, _y, _z)
>   }
>   point(x, y, z)
> }
> 2009/5/21 Ricky Clarkson <ricky.clarkson@...>
>>
>> val (x, y, z) = {
>> val a = 1 + 2
>> val b = 3 + 4
>> (a + 1, a + b, a - b)
>> }
>>
>> 2009/5/21 Rob Dickens <arctic.bob@...>:
>> > Dear Martin and All,
>> > One good thing Java still has going for it IMO is its ability, thanks to
>> > its
>> > 'blank finals', always to let you confine the scope of local variables
>> > to
>> > where they're used - thus resulting in more maintainable code.
>> > For example,
>> > void javaVersion() {
>> >   final int x, y, z; {
>> >    final int a = 1 + 2;
>> >    x = a + 1;
>> >    final int b = 3 + 4;
>> >    y = a + b;
>> >    z = a - b;
>> >   }
>> >   point(x, y, z);
>> > }
>> > To my knowledge, this is currently best translated as,
>> > def scalaVersion() {
>> >   val (x, y, z) = {
>> >    val a = 1 + 2
>> >    val _x = a + 1
>> >    val b = 3 + 4
>> >    (_x, a + b, a - b)
>> >   }
>> >   point(x, y, z)
>> > }
>> > Note the requirement for the shadow val, _x.
>> > Assuming it were feasible to support, and imagining cases with more
>> > complex
>> > expressions, wouldn't the following syntax be more agreeable?
>> > def scalaxVersion() {
>> >   val x, y, z {
>> >    val a = 1 + 2
>> >    x = a + 1
>> >    val b = 3 + 4
>> >    y = a + b
>> >    z = a - b
>> >   }
>> >   point(x, y, z)
>> > }
>> > --
>> > Rob, Lafros.com
>
>

« Return to Thread: idea: val x, y {... x = ... y = ...}