On May 5, 2005, at 2:55 PM, Andrey Melnikov wrote:
Semantically convert_to is a different operation. Safe C++ way to do itoa has nothing to do with serialization.
Then why does the lexical cast documentation specifically compare itself to atoi and strtol: http://www.boost.org/libs/conversion/lexical_cast.htm As stated in the first paragraph on the motivation: "Sometimes a value must be converted to a literal text form, such as an int represented as a string, or vice-versa, when a string is interpreted as an int. Such examples are common when converting between data types internal to a program and representation external to a program, such as windows and configuration files." Working with windows and configuration files, in my experience, at least, requires handling of invalid values. They are the normal case, not an exceptional case. And from reading the lexical_cast documentation, you'd think this is the library to use. Apart from the name containing "cast", lexical_cast does what I need: converting numbers to and from strings.
I think we can leave lexical_cast alone as it is, but add separate functions for safe conversions between ascii and binary representation of numbers. These functions should be fast and properly named according to their semantic. Performance requirement can also force us to implement additional interface with error flag instead of throwing exceptions. convert_to<int>("abc") can be so fast that in some applications overhead of throwing an exception will be very noticeable.
That would work, as well. But I'm thinking that convert_to would need to fall back to lexical_cast for conversion that do not contain a string. If we want to concentrate on the conversion to and from strings, maybe names like string_to and to_string would be more appropriate: int n = string_to<int>("50"); int httpPort = string_to<int>("invalid conversion", 80); And the converse: string message = "Connecting to server: " + host + ":" + to_string(80); Actually, to_string cannot have an invalid conversion case, can it? It seems only going from a string can cause that. And as for performance being an issue, it probably is in some cases. In the cases where I've used string to int conversions and vice vera, performance has not been critical and stringstreams have been just fine, though. I started using lexical_cast because it made my stringstream code easier to read. -Dave