Function Parameters

General
1

I got an external Library and I found something interesting in their Xojo/RB example.

There are a bunch of Constants

CONSTANT_01 = 2 CONSTANT_02 = 4 etc.
and then a Function is Called like this:

aFunction(CONSTANT_01 Or CONSTANT_02)

^ watch the ‘Or’

And the Function looks like this:

[code]Sub aFunction(Optional flags As UInt32 = CONSTANT_01)

Declare Function aFunction Lib aLibrary(ByVal flags As UInt32) As Int32

Dim ret As Int32 = aFunction(flags)

Select Case ret
Case 0 ’ success
Return
Case 8
Raise New someException
Case 15
Raise New someOtherException
etc…[/code]

I had no idea that a Function could be called like this.
Within the function, it seems that the constants are added (flags = 6).
But when I change the ‘Or’ (in the Function Call) to ‘And’, flags = 0.

Is this something handy I missed? How is this normally used? Are there examples in the documentation that explains this and show where this could be useful?

2

http://documentation.xojo.com/index.php/And
http://documentation.xojo.com/index.php/Not
http://documentation.xojo.com/index.php/Or
http://documentation.xojo.com/index.php/Xor

aFunction(CONSTANT_01 Or CONSTANT_02)

takes 2 (integer) OR 4 (integer)

Bitwise OR of 2 and 4 gives 6

2 => &b010
4 => &b100
----------------
     &b110 => 6

You set the bit in the result if it is set in one OR the other

3

Thanks Norman

4

This change to make AND OR NOT XOR also do bitwise operations on integers happened quite a few years back