Re: table.pack()

["Stuart P. Bentley" <stuart@...>]

(Sorry if I'm a bit late to the party- went through a great big machine 
shuffle a while back and didn't re-add the Lua list to my newsgroups until 
now.)


> > I agree with Patrick here. However I'd go a little further and vote for 
> > no
> > 'table.pack' at all. I agree it is useful in some cases and people write
> > something like that often (as does 'string.split', 'table.append',
> > 'table.copy', ...). But I don't believe there is one-version-fits-all to
> > make it into a standard library. Furthermore, the asymmetry with
> > 'table.unpack' [1] and bringing back the 'n' field policy does not look 
> > like
> > the best choice either. Personally, I'd rather see 'apairs' [2] becoming
> > standard.
>
> I would agree that using an 'n' field is an odd about-face for Lua
> after the changes in 5.0 -> 5.1. It would be easier to just return a
> second value and allow the programmer to set his own convention.
>
> I don't agree that table.pack is not useful enough for inclusion. It
> is way too difficult to save the return values of a function without
> creating a new table. Setting unnecessary standards is one thing,
> making a common problem doable is another.

I don't really see the need for table.pack at all- what does it provide over 
{...} and select('#',...)?
Is the table that table.pack returns not a new table?

The table-argument-saving-in function that I'd like to see is the function 
that returns a table that is the equivalent of several tables in its 
argument concatenated. This, in the classic Lua fashion, would have several 
useful applications, including allowing the use of all results from multiple 
function calls with multiple returns (which can't be done with an ordinary 
table constructor as each consecutive function cuts the last one down to one 
return). For example:

function function_with_multiple_returns() return 1,2,3 end

example={
{function_with_multiple_returns()},
{function_with_multiple_returns()},
{function_with_multiple_returns()}
}

Calling this function with the example table would return {1, 2, 3, 1, 2, 3, 
1, 2, 3}.