Re: Feature request: plain option for gsub

[Coroutines <coroutines@...>]

On Fri, Aug 22, 2014 at 11:33 PM, Sean Conner <sean@conman.org> wrote:

>   Okay, now I'm totally confused as to what you are trying to do.  Let's
> take, for example, LPeg.
>
>         > lpeg = require "lpeg" -- I'm using 0.12 BTW
>         > x = lpeg.P "Coroutines"
>         > print(type(x))
>         userdata: 0x8835e7c

>   Okay, what exactly, are you trying to modify?

Okay.  From Lua you have a userdata object.  You can use # to get the
size of that, assuming __len isn't doing anything deceptive.  I want
to be able to string.sub() userdata, so I can read
character-by-character.  Promoting a lua_Buffer/userdata to a string
hashes the userdata and from then on it's known as a string to Lua,
and I cannot modify it.  But I don't need that hash or the inherent
deduplication -- I know that the data in that userdata is unique and
its lifetime is short (it's a packet!).  I want to be able to read
userdata from Lua without touching C -- without writing a function to
dump userdata as a string.  I want to operate *ON* the userdata, not a
string copy.  The point is avoiding more allocation when I just need 1
buffer that is very volatile.

>         typedef struct lua_State lua_State;
>
> and that's it.  No indication of how big it is, or what's inside it.  Try to
> compile the following:

I am not talking about opaque types in C :>

>   I also don't fully understand what you mean by:
>
>> I dream of a world without data channels and serializing things

The cost of serializing an object and sharing it through some method
of IPC is more than it needs to be.  I take issue with the concept of
it.  When I have brought this up before I'm told to look elsewhere for
inefficiency, but I am someone who likes to solve benign problems.
Also lock-free algorithms are a thing.  Message-passing will never be
as quick as zero-copied, shared data ;>