Math

[dennis]

When I try something like:

print Math.sin(Math.pi / scale)

(scale is a Double)

I get errors like:

Cannot apply SLASH to Double.

Cannot find a definition for "pi" in "Math".

Do I need to do some sort of type casting or overloading that I'm overlooking?

[Charles]

Since Cobra member access starts with a lower case letter, it's "pI". Certainly "pi" should be accepted and I'll enhance this. Not sure about the other error. I'd have to see the rest of your code. This works for me:

class X
    def main is shared
        scale = 1.0f
        print Math.sin(Math.pI / scale)

To reduce the ugliness, you could say:

pi = Math.pI

And use "pi" from then on.

[dennis]

I didn't think to try that capitalization.

Here is a sample of code that produces the SLASH error:

"""
MathTest.cobra
"""

class MathTest

    shared
    
        var _c as Double
        
        def main
        
            _c = 35.12 to Double
            d = 1.456 to Double
            print _c / d

In my code, I can probably do the arithmetic in another type, but I need to cast it to Double to pass it to the trig methods. And it would require doing about twice as many type casts that way.

[dennis]

Using float instead of Double takes care of the SLASH error.

[Charles]

Right, Cobra's primitive types for numbers are now:

• int, uint (default 32 bits)
• int8, int16, int32, int64, uint8, uint16, uint32, uint64
• decimal
• float

The float is 64-bits. There will be a float32 and float64 some day.

Suffixes:

• f for float. ex: 1.5f
• d for decimal, but this is optional as it's the default.
• for integers, cast to the type: 1 to int64

We'll likely need suffixes for the integers as well so you can have a 64-bit literal without "breaking it down" into an arithmetic expression. My current thought for int suffixes would be, for example, "100i64" and "100u64" for signed and unsigned.

Also, you can put underscores in numbers like so: "i = 10_000_000". That's 10 million. Works for floats and decimals too.