Re: Feature request: plain option for gsub

[Coroutines <coroutines@...>]

On Sun, Aug 24, 2014 at 7:40 PM, Sean Conner <sean@conman.org> wrote:

>   Because elsewhere you said:
>
>> I would like the option of peering into and modifying any userdata
>> from Lua as if it were a string, with the string functions.  This
>> would break security so I'd want to control this ability through the
>> debug library.
>
>   That's why.  So, yeah, LPeg example.

I was joking that for a userdata example you brought in LPeg -- which
not many people understand (myself included at times).

>   In C, a structure is just a sequence of bytes.  In C, a string is just a
> sequence of bytes.  Yes, in C, you can cast a structure pointer to a
> character pointer and back again.  It doesn't mean that's a good idea.

This is actually how I was representing my socket type in C -- it was
basically { lua_Stream, fd, SOCKET (HANDLE on Windows) }.

Wherever I needed a lua_Stream because it was the first element I
could cast the pointer to that type -- it was quite handy ;p

These replies feel like "I can't trust you to know what you're doing
so let's argue about it until you lose credibility and interest"...

>   But then don't be surprised when you ask us to help you fail and we
> refuse.  Some of us here have already been down that road and are trying to
> warn you about the dangers ahead.

I didn't know I was specifically asking you for help -- I was only
trying to put forth the idea that mutable, unpooled strings/buffers
have their place.  Anyway, far off the topic of this thread...

>         struct somestruct
>         {
>           int x;
>           int y;
>           char *name;
>         };
>
>   You want to pass that as a message.  It contains a pointer to some string.
> A zero-copy message passing scheme doesn't mean the memory pointed to by
> name is included.  You still have to flatten the thing into a single block
> of memory.

I have been writing C since 2005, I understand references -- this is
starting to feel like I'm being talked down to...

I told you before I was only trying to use userdata for a buffer to
recv() into.  I understand the perils of looking at structs
represented through userdata (from padding & alignment to references).

>   And even a function call copies data ...

Wait... so you're saying the stack and registers are used for something? :p