how are variables passed from functions?

[Mike Bonner]

The value returned in the previous scenario (basing the return on 10 being
the number used) is 20. The final doubling disappears.

On Fri, Nov 14, 2014 at 10:40 AM, Mike Bonner <bonnmike at gmail.com> wrote:

> For anything other than this simple case, the returns matter.
>
> Take for example
>
> local tvar1,tvar2,tvar3
> on mouseUp
> --get a random value to use
>    put random(10) into tvar1
>    put "Start Value: " & tvar1 & cr & "Final Return:" &  myfunc1(tvar1) &
> cr & tvar3
> end mouseUp
>
> function myfunc1 pvar
>    put 2 * myfunc2(pvar) into tVar2
>    return tvar2
>
> end myfunc1
>
> function myfunc2 pvar
>    put pvar * 2 into tvar3
>    return tvar3
> end myfunc2
>
> With this function, if the random number is 10,  the value returned from
> the function is 40, doubled twice once by each function.
> the double in the 3rd function happens PRIOR to the execution of the
> second function (the end of the chain is first working backwards)
> So tvar3 (in the last function) is the first double, so the value in tvar3
> will be 20.  Then the other double is done and placed into tvar2. So the
> value returned will be 40.
>
> If you remove the return from myfunc1, the final doubling isn't returned.
> The value of tvar2 IS 40, but its never returned, so you end up with an
> unanticipated return, the return (which as discovered earlier) is "the
> result" from the whole chain.  Since the only actual result is from
> muFunc2, that is the value that ends up being returned to the original
> function call.
>
> On Fri, Nov 14, 2014 at 10:02 AM, Jacques Hausser <jacques.hausser at unil.ch
> > wrote:
>
>> Yes, it is ’the Result’, I just checked it - good hint, Dave ! didn’t
>> think about that before…
>>
>> Jacques
>>
>> > Le 14 nov. 2014 à 17:56, Dave Cragg <dave.cragg at lacscentre.co.uk> a
>> écrit :
>> >
>> > Tiemo,
>> >
>> > Interesting. It looks like functions return the value of "the result"
>> in the absence of a return statement.
>> >
>> > Other languages would probably return "void" or "null" or something
>> similar, and we might expect Livecode to return "empty".
>> >
>> > I've no opinion on whether it is a bug or not, but I think it is
>> probably better to specifically return a value from a function. We don't
>> always have control over what appears in "the result".
>> >
>> > Cheers
>> > Dave
>> >
>> >
>> >
>> > On 14 Nov 2014, at 08:47, Tiemo Hollmann TB <toolbook at kestner.de>
>> wrote:
>> >
>> >> By accident I noticed that I don't have a return at a certain point of
>> a
>> >> function but nevertheless the value was passed back without a return
>> to the
>> >> calling handler.
>> >>
>> >> I can reproduce the issue to this scenario:
>> >>
>> >>
>> >>
>> >> --Btn script
>> >>
>> >> on mouseUp
>> >>
>> >>   put foo1() into myVar1 -- I get the value "Test"
>> >>
>> >> end mouseUp
>> >>
>> >>
>> >>
>> >> --script in stack
>> >>
>> >> function foo1
>> >>
>> >>  put foo2() into myVar2 -- no return in this function
>> >>
>> >> end foo1
>> >>
>> >>
>> >>
>> >> function foo2
>> >>
>> >>  return "Test" -- return here in second level
>> >>
>> >> end foo2
>> >>
>> >>
>> >>
>> >> Up to now I thought that every function has to have a return statement
>> if
>> >> you want anything getting back.
>> >>
>> >> Can somebody explain to me what is going on here? How is the value from
>> >> function foo2 passed back to the mouseup handler, even with different
>> var
>> >> names?
>> >>
>> >> Is this a bug or just an accident or even wanted?
>> >>
>> >> Thanks for enlightening
>> >>
>> >> Tiemo
>>
>>
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>
>