Thread: adding method to STL class

Can I do that? I just wrote a "tokenize string" function:

Code:

vector<string> tokenize(string &str, string tokens);

and then thot, well, why not do this:

Code:

vector<string> string::tokenize(string tokens);

However, I get "error: too few template-parameter-lists" for that line...

To add members to a class, well, you need source for the class (because that name has to appear in the definition). And then, of course, almost by definition, you are no longer in std::string, but MK27::string.

I've never tried to inherit from a STL class (which seems like the next most obvious choice), but I remember hearing that it usually fails horribly since the STL wasn't really designed for that sort of thing.

(ETA: And of course, since string is a template class with (at least) three templated arguments (i.e., string<charT, traits, allocator>) you would have to have that in your definition as well.)

Free functions are they way to go if you want to extend the interface of existing classes.

Probably not worth the bother then.

Originally Posted by tabstop

I've never tried to inherit from a STL class (which seems like the next most obvious choice), but I remember hearing that it usually fails horribly since the STL wasn't really designed for that sort of thing.

I believe the caveat has to do STL classes not having virtual functions, so:

Code:

string *ptr = new myDerivedClass(...

will foul up.

There is no point in writing a wrapper class; writing a free function like what you did will do.