Better dstream:

* non-Windows dstream is a simple reference alias
* dstream constructor takes a target ostream argument
* dstream inherits the unitbuf setting of the target stream

extras/beast/unit_test/dstream.hpp

@@ -8,11 +8,10 @@
 #ifndef BEAST_UNIT_TEST_DSTREAM_HPP
 #define BEAST_UNIT_TEST_DSTREAM_HPP
 
-#include <boost/utility/base_from_member.hpp>
-#include <iostream>
+#include <ios>
 #include <memory>
 #include <ostream>
-#include <sstream>
+#include <streambuf>
 #include <string>
 
 #ifdef _MSC_VER
@@ -30,15 +29,18 @@
 namespace beast {
 namespace unit_test {
 
-namespace detail {
-
 #ifdef _MSC_VER
 
+namespace detail {
+
 template<class CharT, class Traits, class Allocator>
 class dstream_buf
     : public std::basic_stringbuf<CharT, Traits, Allocator>
 {
+    using ostream = std::basic_ostream<CharT, Traits>;
+
     bool dbg_;
+    ostream& os_;
 
     template<class T>
     void write(T const*) = delete;
@@ -47,21 +49,21 @@ class dstream_buf
     {
         if(dbg_)
             OutputDebugStringA(s);
-        else
-            std::cout << s;
+        os_ << s;
     }
 
     void write(wchar_t const* s)
     {
         if(dbg_)
             OutputDebugStringW(s);
-        else
-            std::wcout << s;
+        os_ << s;
     }
 
 public:
-    dstream_buf()
-        : dbg_(IsDebuggerPresent() != FALSE)
+    explicit
+    dstream_buf(ostream& os)
+        : os_(os)
+        , dbg_(IsDebuggerPresent() != FALSE)
     {
     }
 
@@ -79,66 +81,52 @@ public:
     }
 };
 
-#else
-
-template<class CharT, class Traits, class Allocator>
-class dstream_buf
-    : public std::basic_stringbuf<CharT, Traits, Allocator>
-{
-    template<class T>
-    void write(T const*) = delete;
-
-    void write(char const* s)
-    {
-        std::cout << s;
-    }
-
-    void write(wchar_t const* s)
-    {
-        std::wcout << s;
-    }
-
-public:
-    ~dstream_buf()
-    {
-        sync();
-    }
-
-    int
-    sync() override
-    {
-        write(this->str().c_str());
-        this->str("");
-        return 0;
-    }
-};
-
-#endif
-
 } // detail
 
-/// A std::ostream that redirects output to the debugger if attached.
+/** std::ostream with Visual Studio IDE redirection.
+
+    Instances of this stream wrap a specified `std::ostream`
+    (such as `std::cout` or `std::cerr`). If the IDE debugger
+    is attached when the stream is created, output will be
+    additionally copied to the Visual Studio Output window.
+*/
 template<
     class CharT,
     class Traits = std::char_traits<CharT>,
     class Allocator = std::allocator<CharT>
 >
 class basic_dstream
-    : private boost::base_from_member<
-        detail::dstream_buf<CharT, Traits, Allocator>>
-    , public std::basic_ostream<CharT, Traits>
+    : public std::basic_ostream<CharT, Traits>
 {
+    detail::dstream_buf<
+        CharT, Traits, Allocator> buf_;
+
 public:
-    basic_dstream()
-        : std::basic_ostream<CharT, Traits>(&this->member)
+    /** Construct a stream.
+
+        @param os The output stream to wrap.
+    */
+    explicit
+    basic_dstream(std::ostream& os)
+        : std::basic_ostream<CharT, Traits>(&buf_)
+        , buf_(os)
     {
+        if(os.flags() && std::ios::unitbuf)
+            std::unitbuf(*this);
     }
 };
 
 using dstream = basic_dstream<char>;
 using dwstream = basic_dstream<wchar_t>;
 
-} // test
+#else
+
+using dstream = std::ostream&;
+using dwstream = std::wostream&;
+
+#endif
+
+} // unit_test
 } // beast
 
 #endif

extras/beast/unit_test/main.cpp

@@ -99,7 +99,8 @@ int main(int ac, char const* av[])
     po::store(po::parse_command_line(ac, av, desc), vm);
     po::notify(vm);
 
-    dstream log;
+    dstream log{std::cerr};
+    std::unitbuf(log);
 
     if(vm.count("help"))
     {