update examples

example/execution_context/parameter.cpp

@@ -0,0 +1,55 @@
+
+//          Copyright Oliver Kowalke 2014.
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <string>
+
+#include <boost/context/all.hpp>
+#include <boost/lexical_cast.hpp>
+
+class X{
+private:
+    int * inp_;
+    std::string outp_;
+    std::exception_ptr excptr_;
+    boost::context::execution_context caller_;
+    boost::context::execution_context callee_;
+
+public:
+    X():
+        inp_( nullptr),
+        outp_(),
+        excptr_(),
+        caller_(boost::context::execution_context::current()),
+        callee_(boost::context::fixedsize_stack(),
+             [=](){
+                try {
+                    int i = * inp_;
+                    outp_ = boost::lexical_cast<std::string>(i);
+                    caller_.resume();
+                } catch (...) {
+                    excptr_=std::current_exception();
+                }
+             })
+    {}
+
+    std::string operator()(int i){
+        inp_ = & i;
+        callee_.resume();
+        if(excptr_){
+            std::rethrow_exception(excptr_);
+        }
+        return outp_;
+    }
+};
+
+int main() {
+    X x;
+    std::cout<<x(7)<<std::endl;
+    std::cout << "done" << std::endl;
+}