default_value

src/cxxopts.hpp

@@ -3,6 +3,7 @@
 #include <map>
 #include <exception>
 #include <boost/any.hpp>
+#include <sstream>
 
 namespace cxxopts
 {
@@ -21,7 +22,27 @@ namespace cxxopts
 
   namespace values
   {
-    class Boolean : public Value
+    template <typename T>
+    class default_value : public Value
+    {
+      void
+      parse(const std::string& text, any& result) const
+      {
+        T t;
+        std::istringstream is(text);
+        is >> t;
+        result = t;
+      }
+
+      bool
+      has_arg() const
+      {
+        return true;
+      }
+    };
+
+    template <>
+    class default_value<bool> : public Value
     {
       void
       parse(const std::string& text, any& result) const
@@ -36,7 +57,8 @@ namespace cxxopts
       }
     };
 
-    class String : public Value
+    template <>
+    class default_value<std::string> : public Value
     {
       void
       parse(const std::string& text, any& result) const
@@ -52,6 +74,13 @@ namespace cxxopts
     };
   }
 
+  template <typename T>
+  std::shared_ptr<Value>
+  value()
+  {
+    return std::make_shared<values::default_value<T>>();
+  }
+
   extern std::basic_regex<char> option_matcher;
 
   extern std::basic_regex<char> option_specifier;
@@ -293,10 +322,11 @@ namespace cxxopts
       const std::string& opts, 
       const std::string& desc,
       std::shared_ptr<const Value> value
-        = std::make_shared<values::Boolean>()
+        = ::cxxopts::value<bool>()
     );
 
     private:
     Options& m_options;
   };
+
 }

src/main.cpp

@@ -31,7 +31,7 @@ int main(int argc, char* argv[])
   options.add_options()
     ("a,apple", "an apple")
     ("b,bob", "Bob")
-    ("f,file", "File", std::make_shared<cxxopts::values::String>())
+    ("f,file", "File", cxxopts::value<std::string>())
   ;
 
   options.parse(argc, argv);
@@ -48,7 +48,8 @@ int main(int argc, char* argv[])
 
   if (options.count("f"))
   {
-    std::cout << "File = " << boost::any_cast<std::string>(options["f"]) << std::endl;
+    std::cout << "File = " << boost::any_cast<std::string>(options["f"]) 
+      << std::endl;
   }
 
   } catch (const std::regex_error& e)