decouple zip operator from observable

made changes to the operator implementation pattern. using zip as the
first example.
allows rx-lite.hpp to not include the operators and instead have the
app explicitly include only the operators needed.
allows all zip related logic to be only in the rx-zip.hpp. observable
only has a forwarding function named zip and operators define zip_tag
and its include_header member.
improves docs by linking the observable and free operator methods to
the single doc at file scope.
operator_member_missing overloads allow static asserts to help usage.
the include_header member of the zip_tag allows a static assert to ask
for the zip file to be included when omitted in rx-lite mode

3 files changed, 11 insertions, 7 deletions

diff --git a/Rx/v2/examples/doxygen/main.cpp b/Rx/v2/examples/doxygen/main.cpp
index 0c7c351..8a831f2 100644
--- a/Rx/v2/examples/doxygen/main.cpp
+++ b/Rx/v2/examples/doxygen/main.cpp
@@ -1,2 +1,11 @@
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
+
+#include <iostream>
+#include <thread>
+#include <string>
+std::string get_pid() {
+    std::stringstream s;
+    s << std::this_thread::get_id();
+    return s.str();
+}
diff --git a/Rx/v2/examples/doxygen/range.cpp b/Rx/v2/examples/doxygen/range.cpp
index 7b84d7f..69eecbd 100644
--- a/Rx/v2/examples/doxygen/range.cpp
+++ b/Rx/v2/examples/doxygen/range.cpp
@@ -13,12 +13,7 @@ SCENARIO("range sample"){
     printf("//! [range sample]\n");
 }
 
-#include <iostream>
-std::string get_pid() {
-    std::stringstream s;
-    s << std::this_thread::get_id();
-    return s.str();
-}
+std::string get_pid();
 
 SCENARIO("threaded range sample"){
     printf("//! [threaded range sample]\n");
diff --git a/Rx/v2/examples/doxygen/zip.cpp b/Rx/v2/examples/doxygen/zip.cpp
index 9085110..c5cd07b 100644
--- a/Rx/v2/examples/doxygen/zip.cpp
+++ b/Rx/v2/examples/doxygen/zip.cpp
@@ -51,7 +51,7 @@ SCENARIO("Selector zip sample"){
     auto o1 = rxcpp::observable<>::interval(std::chrono::milliseconds(1));
     auto o2 = rxcpp::observable<>::interval(std::chrono::milliseconds(2));
     auto o3 = rxcpp::observable<>::interval(std::chrono::milliseconds(3));
-    auto values = o1.zip(
+    auto values = o1 | rxcpp::operators::zip(
         [](int v1, int v2, int v3) {
             return 100 * v1 + 10 * v2 + v3;
         },