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| Re: [xtend] Floating Point number and expressions with them [message #776952 is a reply to message #776164] |
Mon, 09 January 2012 15:26  |
 Sebastian Zarnekow
Messages: 3118
Registered: July 2009 |
Senior Member |
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Hi Tom,
this should be solved in the latest version from Xtext HEAD. Stay tuned
for the next milestone.
Regards,
Sebastian
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Am 07.01.12 18:36, schrieb Tom Schindl:
> Hi,
>
> here's a an method-definition is created to extrac the red value of a
> hex-color definition (e.g. #FF0000).
>
> ---------8<---------
> def red(String color) {
> return Integer::valueOf(color.substring(1,3),16) /
> Double::valueOf('255.0');
> }
> ---------8<---------
>
> You'll notice my first problem is that I'm unable to use floating point
> literals (first problem) so i created a double using the valueOf-method.
>
> The real problem though is that you are translating to Java code like this:
>
> ---------8<---------
> public int red(final String color) {
> String _substring = color.substring(1, 3);
> Integer _valueOf = Integer.valueOf(_substring, 16);
> Double _valueOf_1 = Double.valueOf("255.0");
> int _operator_divide = IntegerExtensions.operator_divide(_valueOf,
> _valueOf_1);
> return _operator_divide;
> }
> ---------8<---------
> which means the result of this operation is an integer just like I would
> have written x / 255.
>
> To make the code act equal to java expressions one has to write:
>
> ---------8<---------
> def red(String color) {
> return Integer::valueOf(color.substring(1,3),16) as double /
> Double::valueOf('255.0');
> }
> ---------8<---------
>
> I think it is incorrect to derive the result of an operation from the
> first operand (at least in Java itself the result of an operation is in
> the area of the biggest operand and not the first one which would be in
> the original statement Double).
>
> So here are my 2 problems:
> a) Isn't there a shorter way to define a floating point number
> b) Is it a bug or by design that the operation is happening in the area
> of the first operand?
>
> Tom
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