I need some guidance or pointers understanding how to implement a custom ostream. My requirements are:
- A class with a '<<' operator for several data types.
- The intention is to send output to database. Each "line" should go to a separate record.
- Each record most important field would be the text (or blob), but some other fields such as time, etc. can be mostly deduced automatically
- buffering is important, as I don't want to go to database for every record.
First, does it worth deriving from ostream? What do I get by deriving from ostream? What if my class simply implements few opeartor<< methods (including some custom data types). Which functionality do I get from ostream?
Assuming what I want is a class derived from ostream, I need some guidance understanding the relationship between the ostream and the streambuf classes. Which one do I need to implement? Looking at some samples, at appears I get manage by not deriving from ostream at all, and just giving the ostream constructor a custom streambuf. Is that true? is that the canonical approach?
Which virtual functions at the custom streambuf do i need to implement? I've seen some samples (including this site: here and here, and few more), some override the sync method, and other override the overflow method. Which one should I override? Also, looking at the stringbuf and filebuf sources (Visual Studio or GCC) both those buffer classes implement many methods of the streambuf.
If a custom class derived from streambuf is required, would there be any benefit deriving from stringbuf (or any other class) instead of directly from streambuf?
As for "lines". I would like at least when my users of the class using the 'endl' manipulator to be a new line (i.e. record in database). Maybe - depends on effort - every '\n' character should be considered as a new record as well. Who do my custom ostream and/or streambuf get notified for each?
