🚀 go-pugleaf

In article 95Sep26142017@slbwa7.bln.sel.alcatel.de, prange@slbwa7.bln.sel.alcatel.de (Martin Prange) writes:
>
>
>To make the operator(s) << (from iostream.h) usable by other classes,
>they must be derived by the appropriate iostream-class.
>
>As non-member functions they could be used by any class, 
>that could be casted to (ostream&) by means of e.g. operator ostream&.
>( Which is, what I actually wanted to. )
>
>So, the question is:
>Why are these operators declared (and implemented , of course), as members ?
>Are there design issues I`ve been missing so far?

The design decision for iostreams was that the istream and ostream 
conversion functions have a single definition. For that reason they were
made non-virtual member functions. When you use those conversion
functions inside your own I/O functions, such as
	ostream& operator<<(ostream& o, const MyClass& m)
	{	... o << m.i ...	}
you always know exactly what you will get.

Other designs are possible, but that was the reason. People differ on
whether that was the best possible choice.

---
Steve Clamage, stephen.clamage@eng.sun.com



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