Re: keyboard selection

[Richard Frith-Macdonald]

On 20 Aug 2007, at 14:26, Fred Kiefer wrote:

> Riccardo wrote:
> > Hello,
> >
> > inside textfields (GNUMail message editing and Ink are an example) I
> > think I used to be able to select text using shift + arrows  
> > movment. I
> > notice today that it is not possible. Is it a bug? Or am I just  
> > used to
> > do it on other platforms?
>
> Thank you for spotting this. The reason for this was really hard to
> track down. It turns out to be the following line in NSInputManager:
>
> BOOL isFunctionKey = [theEvent modifierFlags] & NSFunctionKeyMask;
>
> This used to work while the value for NSFunctionKeyMask was in the  
> first
> byte, but now it is 1<<24 and the resulting BOOL was NO.
> This should be a warning to all of us to program more careful and  
> always
> use explicit comparisons for integer masks. This code does the trick:
>
> BOOL isFunctionKey = ([theEvent modifierFlags] & NSFunctionKeyMask)
>         == NSFunctionKeyMask;

Well spotted!

though I prefer the even more explicit setting of YES or NO as in

BOOL isFunctionKey = (([theEvent modifierFlags] & NSFunctionKeyMask)  
== NSFunctionKeyMask) ? YES : NO;

as this guarantees that a test of the form 'if (isFunctionkey ==  
YES)' will work correctly.

I also try to always write code to test 'if (x == YES)'  rather than  
'if (x)', as it will fail in more cases (and hopefully cause us to  
spot errors like that) if someone has done something like assigning a  
bitmask to a boolean.

Not a big issue, just a bit of coding style that I've found helps  
code reliability over the years.