Shrenik Shah <[email protected]> asks about combining the -by:- prefix with
class programming.
> It seems that the byable option does not work correctly when used
> with a class member program. (I am using Stata Version 8.2.) For
> example, if I try to create a test class:
> version 8.2
> class testclass {
> }
> program .test, byable(recall)
> if _by() {
> disp "by option worked"
> }
> end
>
> I find:
>
> . .tc = .testclass.new
>
> . sort index
>
> . by index: .tc.test
> unrecognized command: .tc.test invalid command name
> r(199);
The -by:- prefix cannot be combined with class member programs because in a
line like
. by index: .tc.test
-by:- is modifying a class instance (.tc) and not a program (.test). In
short, -by:- is not meant to work with member programs.
I have a hard time envisioning how the -by:- prefix could be more useful when
operating on a member program within a specific class instance rather than
operating on normal program, but that does not matter, Shrenik can get his
desired result with a simple wrapper program. For example,
---------------------------------- BEGIN --- classby.ado --- CUT HERE -------
version 8.2
program classby, byable(recall)
`0'
end
---------------------------------- END --- classby.ado --- CUT HERE -------
With -classby- in hand, rather than calling -.tc.test- directly, Shrenik can
now type,
. by index: classby .tc.test
If the program -.test- needs any of the local macros passed to a byable
program (and this is unusual for byable(recall) programs), he will need to
pass them along where the `0' appears in program -classby-. For more on these
macros, see [P] byable.
-- Vince
[email protected]
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