Can Handler Know What Params It Should Have
-hh
hh at livecode.org
Tue Feb 2 15:16:52 EST 2016
Bernard wrote:
> I know the params can be called to find out what parameters were
> passed to the handler when it is called. However, I'm wondering
> if a handler has a way of knowing what parameters it had at the
> time it was defined. I don't think so. Regards Bernard
Yes, that's my opinion too, for user handlers, but not for LC/reserved
handlers. This is the simple explanation I use for myself:
[1] For any *user handler*, the answer is NO, because there are
not "the parameters" in a definition. For example
on handler x1,x2
put ( x1,x2 )
end handler
is equivalent to
on handler
put ( param(1),param(2) )
end handler
[2] For a *LC handler* we can see the defined params by calling the
params in the handler without params. For example
on mouseUp
put the params
end mouseUp
yields: MouseUp "1" (if left-clicked)
Means: We can use, where b is the 'reserved' LC param, for example
on mouseUp b,x1,x2
put (x1,x2)
end mouseUp
or equivalently
on mouseUp
put (param(2),param(3))
end mouseUp
=======
Hermann
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