neveu@fugitive.berkeley.edu (Charles Neveu) (07/18/90)
I have a question about SEL variables. How do you initialize a SEL variable to have an invalid, or null, value. That is, I have a SEL variable that I want to initialize to a value that is invalid; some part of the program will set the value to a valid selector; another part of the program will check the value to determine whether it is valid and if it is, send that message to an object. So what do I initialize the variable to? 0? -1? (int) NULL? Thanks, Charles
shiffman@sumex-aim.stanford.edu (Smadar Shiffman) (07/18/90)
In his posting from Jul 18 neveu@fugitive.berkeley.edu writes >I have a question about SEL variables. How do you initialize a SEL variable >to have an invalid, or null, value. That is, I have a SEL variable that I >want to initialize to a value that is invalid; some part of the program will >set the value to a valid selector; another part of the program will check >the value to determine whether it is valid and if it is, send that message >to an object. >So what do I initialize the variable to? 0? -1? (int) NULL? SEL is defined in /usr/include/objc/objc.h : typedef unsigned int SEL; As far as I know 0 is not used for any selector (you can see that by requesting 'info selector' when running gdb with some application). I would try using 0 as an 'invalid' selector. Smadar -------