From the documentation of the StringPiece class in Chromium's source code:
// A string-like object that points to a sized piece of memory.
//
// Functions or methods may use const StringPiece& parameters to accept either
// a "const char*" or a "string" value that will be implicitly converted to
// a StringPiece.
//
// Systematic usage of StringPiece is encouraged as it will reduce unnecessary
// conversions from "const char*" to "string" and back again.
Example of use:
void foo(StringPiece const & str) // Pass by ref. is probably not needed
{
// str has same interface of const std::string
}
int main()
{
string bar("bar");
foo(bar); // OK, no mem. alloc.
// No mem. alloc. either, would be if arg. of "foo" was std::string
foo("baz");
}
This seems like such an important and obvious optimization that I can't understand why it's not more widespread, and why a class similar to StringPiece is not already in the standard.
Are there any reasons why I shouldn't replace the use of string and char* parameters in my own code with this class? Is there anything like it already in the C++ standard libraries?
UPDATE. I've learnt that LLVM's source uses a similar concept: the StringRef class.