Using 'try'

[Alex Tweedly]

Mark Wieder wrote:

> <snip>
>
> but basically the "try"
>construct here lets me set the field to empty without running into a
>runtime error. Without the try the code would give me an error on the
>first line if pValue is empty, since it would try to execute
>
>if < 0 then
>
>  
>
Mark,

I see the general point (any error within the "try" clause will be 
ignored), I don't see the need for it in this case.

I can't find any case where comparing "empty" against a value gives an 
error; I tried it in simple code, as a handler and as a setProp, and 
none of them gives an error.

> on mouseUp
>     put empty into t
>     if t < 0 then
>         put "less"
>     end if
>     myHandler
>     set the NewValue of me to empty
> end mouseUp
>
> on myHandler pVar
>     if pVar < 0 then
>         put "it is less" after msg
>     else
>         put "greater" after msg
>     end if
>     put "it is done" after msg
> end myHandler
>
> setProp NewValue pVar
>     if pVar < 0 then
>         put "it is less" after msg
>     else
>         put "greater" after msg
>     end if
>     put "it is done" after msg
> end NewValue
>
as far as I can tell, none of these give run time errors (Win XP, 2.6.1)

Am I missing a case where this comparison gives a problem ?
Or was it just an example and I shouldn't read too much into the 
specific case used ?

-- 
Alex Tweedly       http://www.tweedly.net



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