xproperty: add package (#2608)

* xproperty: add package

* disable plat

packages/x/xproperty/xmake.lua

@@ -0,0 +1,29 @@
+package("xproperty")
+    set_kind("library", {headeronly = true})
+    set_homepage("https://github.com/jupyter-xeus/xproperty")
+    set_description("Traitlets-like C++ properties and implementation of the observer pattern")
+    set_license("BSD-3-Clause")
+
+    add_urls("https://github.com/jupyter-xeus/xproperty.git")
+    add_versions("2021.04.13", "4e5cc851733ad5f57dd75c33d3beb75aba2569aa")
+
+    add_deps("cmake", "xtl")
+
+    on_install("windows", "linux", "macosx", function (package)
+        import("package.tools.cmake").install(package)
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include <xproperty/xobserved.hpp>
+            struct Foo : public xp::xobserved<Foo>
+            {
+                XPROPERTY(double, Foo, bar);
+                XPROPERTY(double, Foo, baz);
+            };
+            void test() {
+                Foo foo;
+                XOBSERVE(foo, bar, [](Foo& f){});
+            }
+        ]]}, {configs = {languages = "c++14"}}))
+    end)