[boost] Re: Re: [iostreams] Major interace changes planned -- comments requested

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2005-03-09 17:02:29

Rob Stewart wrote:

> Let's review.  There are several things one needs to do with a
> basic_character:
>
>    - return it from a function
>    - test it to determine success
>    - compare it to a char/wchar_t
>
> Have I missed anything?

See below.

> Given those requirements the class needs:
>
>    - value semantics
>    - safe-bool conversion
>    - comparisons with char/wchar_t
>
> Therefore, I think this will work:

<snip synopsis of basic_character with lots of operator overloading>

> Now you can write both of these:
>
>    if (c = get(src))
>
>    if (c == comment_char_)

Suppose you write a filter which expect ASCII characters. You might want to
perform arithmetic operations on characters, e.g.

    if (c >= 65 && c < 91)
        c += 32; // Convert to lowercase.

This may turn out to be pretty common. So we need +, -, +=, -=, too. Also, this
ignores named functions which we might want to pass a character to, and the
operations that a custom character type might support.

I'm not sure if the safe-bool conversion is worth all this trouble. Fortunately,
it's not a majpr design change. I'll soon be writing lots of non-blocking
filters, and I can try both versions.

Jonathan