Re: A Question of Style

[Rebel Neurofog <rebelneurofog@...>]

On Mon, Nov 28, 2011 at 2:03 PM, Jerome Vuarand
<jerome.vuarand@gmail.com> wrote:
> 2011/11/26 Rebel Neurofog <rebelneurofog@gmail.com>:
>> On Sat, Nov 26, 2011 at 5:03 PM, Marc Balmer <marc@msys.ch> wrote:
>>> Hi
>>>
>>> I have a stylistic question wrt/ calling Lua "callbacks" from a C
>>> program.  I see two obvious approaches:
>>>
>>> 1) Lua code registers callbacks explicitely using a RegisterCallback
>>> function that is provided by the C program; the C program later calls
>>> the callback function when one is registered.
>>>
>>> 2) Lua code does not register callbacks, but the callbacks must be
>>> functions with a certain name, e.g. "MouseMovedCallback"; C code will
>>> then see if a function with the correct name is available in the Lua
>>> state, and if so, call it.
>>>
>>> Are there advantages of one approach over the other?  Are there other
>>> approaches?  If you also use callback written in Lua, which you call
>>> from C, I'd like you to share your opinion (and/or experience).
>>>
>>> I experienced with both forms, I am unsure for which form to go...
>>>
>>
>> I prefer the first case.
>> A function may contain also upvalues.
>> Here's the code:
>>
>> local desktop = widget_system.create_desktop ()
>>
>> -- Case 1
>> input.set_mouse_handler (desktop.mouse_move)
>>
>> -- Case 2
>> function mouse_move_handler (dx, dy)
>>   desktop.mouse_move (dx, dy) -- note, there's no ":" here
>> end
>
> AFAICT there is no difference between the two methods with regards to
> upvalues. Since the function is not a method, the second case can be
> better written as:
>
> -- Case 2
> mouse_move_handler = desktop.mouse_move
>
>

Indeed.
You make me feel old and stupid:(

In fact Case 1 is
REGISTY["some_name"] = some_value

whereas Case 2 is
GLOBALS["some_name"] = some_value

No difference but namespacing.