Parameters for functions and commands

[Bob Sneidar]

In short, yes. Commands can still pass parameters, and as you may not know CAN ALSO RETURN VALUES. The difference is that functions are called with parenthesis and must be put into a variable. eg. 

function bobtest 1, 2
   -- do some stuff
   return true
   -- do some other stuff
end bobtest

Now I can say:

put bobTest(1, 2) into tBobResult -- if you exclude into tBobResult the result will be put into the message

Commands are simply called and then the result variable contains anything put there by the return command ie. 

on bobtest2 pParam1, pParam2
   -- do some stuff
   return true
   -- do some other stuff
end bobtest2

Now I can say:

bobtest 1,2 -- or dispatch "bobtest" to card 1 with 1,2
put the result into tBobResult

NOTE: when a return command is encountered, either in a command or function, the handler is immediately exited and control is returned to the calling handler. So anything after -- do some other stuff WILL NOT EXECUTE. 

I suppose the difference may be somewhat academic, but as a convention, functions are usually used to get information, process it and return values without actually "doing" anything, like going to a card or putting values into fields etc. Commands actually DO things, but nothing is preventing you from using all commands or all functions. You can see though from the above examples that functions are slightly simpler to code with, requiring one line instead of two to process returned values. It can also make code more readable:

put theInternetDate(the date) into tToday
updateTheRecordDate tToday

Bob S

> On Jan 4, 2018, at 13:30 , Thomas von Fintel via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> I am well aware that I shouldn't expect *everything* in Livecode to be intuitive, but this one bugs me:
> 
> Having a handler like
> 
>    function DoStuff_1 a, b
> 
>       return a
> 
>    end DoStuff_1
> 
> When you do "put DoStuff_1 (2,3)" the result is 2.
> 
> But with
> 
>    on DoStuff_2 a, b
> 
>        put a
> 
>    end DoStuff_2
> 
> The result of DoStuff_2 (2, 3) is 2,3. "put a*b" produces an error.
> 
> This means, parameters are passed differently to command handlers and function handlers. Right?
> 
> Is that the way it should be and why?
> 
> 
> Thanks for your patience
> 
> Thomas
> 
> 
> 
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