On Wednesday, 17 April 2013 at 13:09:45 UTC, Nick Treleaven wrote:
On 15/04/2013 06:00, H. S. Teoh wrote:
Allowing arbitrary predicates and switch-as-expression allows
you to
write code that shows intent very clearly:
// In pseudo-D syntax
void fill(T)(T image, int x, int y) {
image[x,y] = switch {
case isFillable(image,x,y): fillColor;
case isBorder(image,x,y): borderColor;
default: defaultColor;
};
}
We could use a conditional operator chain:
image[x,y] = isFillable(image,x,y) ? fillColor :
isBorder(image,x,y) ? borderColor :
defaultColor;
Naturally - even as statements, a `switch` statement without a
switch expression is no better than a chain of `if`-`else`s.
Now, consider this hackish use of `predSwitch`:
https://gist.github.com/someboddy/5412843
This is actual D code(you need
https://github.com/D-Programming-Language/phobos/pull/1259 to run
it), and it prints:
*****
*...*
*.+.*
*...*
*****
As expected. This does have an advantage over a chain of
`if`-`else`s or ternary operators - you only need to write the
argument list once.
