Rob Stewart wrote:
From: "Jonathan Turkanis" <technews@kangaroologic.com>
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
Those are easy enough to add, so my suggestion still works.
Correct.
The unfortunate thing is that this scheme makes basic_character far more complicated,
Yes, I was hoping to limit the interface to a single conversion operator. I'd hate to see someone just learning the library look up get() in the reference section, click on the return type and be confronted with a monstrous synopsis. Could I present a "fictional" synopsis of basic_character, which doesn't show all the overloads, and include a note explaining the problem?
though it can be presented progressively (start with ctor, safe-bool conversion, value(), good(), eof(), fail(), and would_block(); later discuss comparison operators; still later discuss numeric operators).
ignores named functions which we might want to pass a character to, and the operations that a custom character type might support.
I'm thinking now it won't be much of a problem, since the conversion to char will likely be the only admissible conversion in such cases: no one will overload a function to take a basic_character::safe_bool, and if the function is a template, the argument will be deduced as basic_charater.
There's still the value() member function.
True.
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.
I'm sorry you have to duplicate your work, but that is a good way to decide. If there's no clear winner, post examples so we can compare them.
I don't think it will be so bad. I'll write the conditional tests using good() instead of the safe-bool conversion, with the hope that it will work for both versions of basic character. If it does, I can replace occurrences of good() with the safe-bool conversion and throw out the orginal version of basic_character.
Whatever you choose, someone's bound to ask why you didn't do it another way. I suggest adding a FAQ while the decision is still fresh.
Good idea. Jonathan