Re: Question about metamethods

["Soni L." <fakedme@...>]

On 14/02/16 10:41 AM, Geoff Smith wrote:
> Hi
>
>
> I am wondering if  __index & __newindex metamethods can be used to 
> solve this slightly complex specific problem
>
>
> I am trying to wire up Lua to a Windows Gui  function. Lets take an 
> example in C#
>
>
> my C# line inside my binding function is
>
>
> dgv1.Rows[1].Cells[4].Style.BackColor = Color.Yellow;
>
>
> The binding function is called from Lua as below
>
>
> gridSetStyle(1, 4, luaStyleTable)
>
>
> Where arg 1 is rowIndex,  arg 2 is CellIndex and
>
>
> arg 3 luaStyleTable  is { BackColor = Yellow}
>
>
> this works but the syntax in Lua isnt nice to require the line 
> gridSetStyle(1, 4, luaStyleTable)
>
>
> What I am trying to do is get Lua to have a metamethod that triggers 
> and calls that function in the background
>
>
> My preferred lua syntax mimics the C# line, so I would like to trigger 
> a call to that function with something like
>
>
> dgv1.Rows[1].Cells[4].Style.BackColor = "Yellow";
>
>
> I suspect this probably isnt possible, can anyone prove me wrong ? Or 
> alternatively suggest another variation on how to solve it ?
>
>
> Thanks Geoff
Why not dgv1[1][4].Style.BackColor = "Yellow"?

dgv1 would have an __index function that checks if the argument is a 
number. if it is, it attempts to index Rows with it, otherwise it does 
something else.

dgv1[1] would have an __index function that checks if the argument is a 
number. if it is, it attempts to index Cells with it, otherwise it does 
something else.

dgv1[1][4] would have an __index function.

dgv1[1][4].Style would have a __newindex function.

Using functions and userdata instead of tables means you can have it 
dynamically update and thus reflect the internal state better.

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