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Subject: Re: [boost] [string] proposal
From: Dean Michael Berris (mikhailberis_at_[hidden])
Date: 2011-01-26 03:34:07

On Wed, Jan 26, 2011 at 4:09 PM, Matus Chochlik <chochlik_at_[hidden]> wrote:
> On Mon, Jan 24, 2011 at 12:59 PM, Dean Michael Berris
>> Right, but what's keeping that person from creating an std::string
>> from this hypothetical `boost::string` if they really need a c_str()?
> In the last couple of days I browsed through
> some of the code that I wrote or that I have access
> to and this is not some marginal use-case.

I can say the same thing, although I'm largely concerned about
"changing the way people think about strings" with an implementation
that actually works and can be adapted in real-world situations rather
than trying to support the IMO borked status quo. ;)

> I don't say that the sources are statistically
> representative or anything, but using string
> to interact with the OS's APIs is actually one of
> the most prevalent use-cases. I don' t think
> it is a good idea to focus on getting the basic string
> manipulation to be uber-efficient at the expense
> of performance of the string in a "real-world" context.

Well, see here's the key phrase there that's important:

  "string manipulation"

I actually want to wipe that phrase off the face of the C++ world and
have everyone think in terms of "building strings" rather than
manipulating them because in reality, there really is no manipulating
something that's unique and immutable -- unless you create a new one
from it.

> Your program does not always look like:
> int main(void)
> {
>  boost::string your_string;
>  do(something(really(cool(and(efficient(with(your_string)))))));
>  return 0;
> }

FWIW, I think programs written that way are just really ugly and broken. ;)

> many time you do things like:
> a) read file, parse its contents, create instances from the data

So, how does immutability change this? Why can't you create an
immutable string from a buffer and parse that immutable string and
create instances of other types from the data?

> b) get string from a socket, manipulate it, display it in the GUI

What's stopping you from building another string from an immutable
string to be displayed in the GUI? If you need something that would be
mutable, you don't use a string to represent it -- use a different
data structure that implies mutability like a vector<char> or similar
data structure, build a string from that and display that string to
the GUI.

> c) get a string from a GUI, save it into a config file

So what's the problem with an immutable string in this context?

> d) take a string literal, localize/translate by gettext, show it
> etc.

Yes (except the gettext part which I largely don't understand), so
what's wrong with building an immutable string from a string literal?
Or for that matter building an immutable string from gettext output?

> In order for this thing to be widely adopted (which is one
> of my goals) it has to be nice to the existing APIs and let's
> face it, most of them expect std::string or just plain ol' char*.

Sure, but still I don't see why you need to add c_str() to an
immutable string when you're fine to create an std::string from that
immutable string and call c_str() from the std::string instance

Dean Michael Berris

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