Re: Strange string.format result

[bil til <biltil52@...>]

Yes, I got it now.

... it is a bit strange and somehow a pity I think ... if you can
concat functions with longer variable return lists is often allowing
to write such commands as, e. g. print( string.format( ...)) MUCH more
compact / readable / safe... . (I think the stack is anyway already in
correct order to just give the return values to the next function - or
would it need a rotation? ... or does this have any "reasonable"
reason?).

Am Sa., 26. Nov. 2022 um 10:45 Uhr schrieb Lars Müller <appgurulars@gmx.de>:
>
> This is just normal Lua vararg handling; string.format is no exception here. Varargs are always truncated to exactly one value - their first value, or nil if there is no first value - if they appear anywhere but at the end of an argument list. Examples:
>
> function varg3() return 1, 2, 3 end
> function varg0() return end
> print(0, varg3()) -- 0, 1, 2, 3 -- not truncated
> print(varg0(), varg3()) -- nil, 1, 2, 3 -- varg0() is truncated to nil
> print(varg3(), varg0()) -- 1 -- varg0() is not truncated to nil, but varg3() is truncated to 1
> print(0, varg3(), varg3(), 2) -- 0, 1, 1, 2 -- varg3() is truncated to 1 both times
>
> On 25.11.22 23:56, bil til wrote:
>
> PS: The following also might be interesting:
>
> do
>
> function Test() return 3, 5 end
> s= string.format( "%d %d", Test(), 4)
> end
>
> s
>
> 3 4
>
> ... so it looks like the '...' of string.format somehow keeps only the
> first return value of Test, except if Test function is the last
> parameter... . Is this normal?
>
> (I thought, that for such "further parameter stripping" it would be
> required to specify this explicitely by brackets like in s=
> string.format( "%d %d", (Test()), 4)? (this gives the same as above,
> in this case it is clear to me...).
>
> Am Fr., 25. Nov. 2022 um 23:46 Uhr schrieb bil til <biltil52@gmail.com>:
>
> If I do the following in Lua 5.4:
>
> do
>
> function Test() return 3, 5 end
> s= string.format( "%d %d %d", 4, Test())
> end
>
> s
>
> 4 3 5
> ... this is as expected...
>
> do
>
> function Test() return 3, 5 end
> s= string.format( "%d %d %d", Test(), 4)
> end
>
> stdin:3: bad argument #4 to 'format' (no value)
> stack traceback:
>         [C]: in function 'string.format'
>         stdin:3: in main chunk
>         [C]: in ?
> ... this somehow does NOT work as I would expect... (I would expect
> that s now is '3 5 4')
>
> (if I debug with breakpoint in str_format, then the top of stack ( int
> top = lua_gettop(L);) is only 3 in this last case... in first case it
> is 4 as expected.... .
>
> Is this some error of Lua, or do I miss here something?