Re: [Boost-users] Fwd: Concatenated input streams

Hi Gavin, hi everyone. I'm thinking about the concatenated input stream concept off and on, and I'd like to ask for some help in organizing a solution. The easy part to me is figuring out how to manage a collection of input doodads (be they streams, stream buffers, sources, or whatever) and satisfy read requests by getting the requested characters from one or more of them. I have some experience with C++ development (from about 20+ years ago, so C++03 is, for better or worse, maybe more familiar to me ...) and so I feel pretty comfortable with the whole business about classes, constructors, methods, etc. What I need is for someone to give me some advice about how to organize the class declarations. Of which existing Boost class should I be deriving from? What is the type of the underlying resources that are to be marshalled? To be a more concrete, here is a snippet of code which uses existing Boost classes to open an input stream. boost::iostreams::file_source fs ("foo.txt"); boost::iostreams::stream_buffer boost::iostreams::file_source sb (fs); std::istream is (&sb); Now I'd like to say something like concatenated_source cs (<list of resources to be marshalled goes here>); boost::iostreams::stream_buffer sb (cs); std::istream is (&sb); What seems obvious to me is to say class concatenated_source: public boost::iostreams::source { ... } but apparently source = device<input> and device says, according to the docs (https://www.boost.org/doc/libs/1_78_0/libs/iostreams/doc/classes/device.html...), template struct device { typedef Ch char_type; typedef see below category; void close(); void close(std::ios_base::openmode); void imbue(const std::locale&); }; Hmm. I was kind of assuming that a generic source would require something about reading some bytes and maybe opening or otherwise creating something to read bytes from, but that doesn't appear to be the case here. Can someone suggest how to organize the declarations for a source or other object from which bytes can be read? I feel pretty certain I can complete the implementation if I can just get off the ground. Thanks in advance for any advice. Robert Dodier