Re: suggestion: table.remove and non-integer keys

[Philipp Janda <siffiejoe@...>]

Am 25.08.2015 um 17:41 schröbte Ulrich Schmidt:
> Am 25.08.2015 um 16:29 schrieb Patrick Donnelly:
> > On Tue, Aug 25, 2015 at 7:14 AM, Rena <hyperhacker@gmail.com> wrote:
> > > Lua strings are immutable (they can't be changed), so there should
> > > never be
> > > multiple copies of a string in one Lua state[1].
> > > [...]
> > > [1] for very short strings it might keep multiple copies when this
> > > would be
> > > more efficient than keeping references, but this is an implementation
> > > detail
> > > that we don't need to know about. :-)
> > You have it reversed. Lua may have multiple copies of large strings
> > but not short strings (len(s) <= 40):
> >
> > http://www.lua.org/source/5.3/lstring.c.html#luaS_newlstr
> Ok now i am completely confused.
> After reading your linked source i am back at my starting point, asuming
> the only value assigned by reference is a table/list. All other are
> assinged by value. So a
> _stringvar1= stringvar2_ creates a copy of the source string.
> (still assuming we are talking about strings of size 1kB+ as in my
> program.)

No. Assignment only manipulates references. You can create new strings via

*   `lua_pushstring`/`lua_pushresult` (from C)
*   concatenation (`x .. y`)
*   a string literal in the cose (e.g. "hello world")
*   file input (e.g. `io.read`)
*   string manipulation (e.g. `s:gsub( "(.)", "%1"` ))
*   ... (basically all function calls that use `lua_pushstring` internally.)

In all theses cases new strings are *not* created if they are short (< 
40 characters) and there already is a string object with the same contents.

> Ulrich.

Philipp