On 03/01/08 04:58, Roland Schwarz wrote:
Larry Evans wrote:
A long time ago, I had one and was intending *eventually* to add it to iostreams, but never got around to it.
[snip]
I am not sure however you noticed the difference to my implementation:
I am storing state _in_ the stream, i.e. in ios base member and thus allowing out << indent_in << "blah blah\n"; out << "still indented\n";
And a function void foo(ostream& os)
that gets passed down my indent_filter'ed stream still knowns the indentation status.
The margin_ostream implements indent operation only the stream object. Does is also have manipulators?
No.
Will margin_ostream also work when downcasted to a plain ostream?
No. However, I've looked further at indent.hpp and the storing of the pointer to the filter in the ios_base using ios_base::pword. What's the advantage of using ios_base::pword to store the pointer to something that's already available via basic_ios<...>::rd_buf and then filtering_streambuf<...>::component<T>(int): http://www.boost.org/doc/libs/1_37_0/libs/iostreams/doc/classes/filtering_st... This design is implemented in boost vault under the "Input - Output" directory in indent_scoped_ostreambuf.zip.