Make all types have ValueLike traits by default.

This allows new types to be added without any fuzz (no need to specify
the traits) if it has operator>>. It also removes the need to manually
specify the ArgTrait for all built in types (such as long, bool, char,
float etc).

ArgTraits now works in the following way:

1) If there exists a specialization of ArgTraits for type X, use it.

2) If no specialization exists but X has the typename
X::ValueCategory, use the specialization for X::ValueCategory.

3) If neither (1) nor (2) defines the trait, use the default which is
ValueLike.

examples/Makefile.am

@@ -1,7 +1,8 @@
 
 noinst_PROGRAMS = test1 test2 test3 test4 test5 test6 test7 test8 test9 \
 			test10 test11 test12 test13 test14 test15 test16 \
-			test17 test18 test19 test20 test21 test22 test23
+			test17 test18 test19 test20 test21 test22 test23 \
+			test24
 
 test1_SOURCES = test1.cpp
 test2_SOURCES = test2.cpp
@@ -26,6 +27,7 @@ test20_SOURCES = test20.cpp
 test21_SOURCES = test21.cpp
 test22_SOURCES = test22.cpp
 test23_SOURCES = test23.cpp
+test24_SOURCES = test24.cpp
 
 AM_CPPFLAGS = -I$(top_srcdir)/include
 

examples/test24.cpp

@@ -0,0 +1,43 @@
+#include "tclap/CmdLine.h"
+#include <iterator>
+
+using namespace TCLAP;
+
+// Define a simple 3D vector type
+struct Vect3D {
+    double v[3];
+
+    std::ostream& print(std::ostream &os) const
+    {
+	std::copy(v, v + 3, std::ostream_iterator<double>(os, " "));
+	return os;
+    }
+};
+
+// operator>> will be used to assign to the vector since the default
+// is that all types are ValueLike.
+std::istream &operator>>(std::istream &is, Vect3D &v)
+{
+    if (!(is >> v.v[0] >> v.v[1] >> v.v[2]))
+	throw TCLAP::ArgParseException(" Argument is not a 3D vector");
+
+    return is;
+}
+
+int main(int argc, char *argv[])
+{
+    CmdLine cmd("Command description message", ' ', "0.9");
+    ValueArg<Vect3D> vec("v", "vect", "vector",
+			 true, Vect3D(), "3D vector", cmd);
+
+    try {
+	cmd.parse(argc, argv);
+    } catch(std::exception &e) {
+	std::cout << e.what() << std::endl;
+	return EXIT_FAILURE;
+    }
+
+    vec.getValue().print(std::cout);
+    std::cout << std::endl;
+}
+

include/tclap/ArgTraits.h

@@ -73,13 +73,46 @@ struct ValueLikeTrait {
  * Arg traits are used to get compile type specialization when parsing
  * argument values. Using an ArgTraits you can specify the way that
  * values gets assigned to any particular type during parsing. The two
- * supported types are StringLike and ValueLike.
+ * supported types are StringLike and ValueLike. ValueLike is the
+ * default and means that operator>> will be used to assign values to
+ * the type.
  */
 template<typename T>
-struct ArgTraits {
+class ArgTraits {
-    typedef typename T::ValueCategory ValueCategory;
+	// This is a bit silly, but what we want to do is:
-	virtual ~ArgTraits() {}
+	// 1) If there exists a specialization of ArgTraits for type X,
-    //typedef ValueLike ValueCategory;
+	// use it.
+	//
+	// 2) If no specialization exists but X has the typename
+	// X::ValueCategory, use the specialization for X::ValueCategory.
+	//
+	// 3) If neither (1) nor (2) defines the trait, use the default
+	// which is ValueLike.
+
+	// This is the "how":
+	//
+	// test<T>(0) (where 0 is the NULL ptr) will match
+	// test(typename C::ValueCategory*) iff type T has the
+	// corresponding typedef. If it does not test(...) will be
+	// matched. This allows us to determine if T::ValueCategory
+	// exists by checking the sizeof for the test function (return
+	// value must have different sizeof).
+	template<typename C> static short test(typename C::ValueCategory*);
+	template<typename C> static long  test(...);
+	static const bool hasTrait = sizeof(test<T>(0)) == sizeof(short);
+
+	template <typename C, bool>
+	struct DefaultArgTrait {
+		typedef ValueLike ValueCategory;
+	};
+
+	template <typename C>
+	struct DefaultArgTrait<C, true> {
+		typedef typename C::ValueCategory ValueCategory;
+ 	};
+
+public:
+	typedef typename DefaultArgTrait<T, hasTrait>::ValueCategory ValueCategory;
 };
 
 #endif

include/tclap/StandardTraits.h

@@ -41,156 +41,10 @@
 
 namespace TCLAP {
 
-// ======================================================================
+// Integer types (signed, unsigned and bool) and floating point types all
-// Integer types
+// have value-like semantics.
-// ======================================================================
 
-/**
+// Strings have string like argument traits.
- * longs have value-like semantics.
- */
-template<>
-struct ArgTraits<long> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * ints have value-like semantics.
- */
-template<>
-struct ArgTraits<int> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * shorts have value-like semantics.
- */
-template<>
-struct ArgTraits<short> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * chars have value-like semantics.
- */
-template<>
-struct ArgTraits<char> {
-    typedef ValueLike ValueCategory;
-};
-
-#ifdef HAVE_LONG_LONG
-/**
- * long longs have value-like semantics.
- */
-template<>
-struct ArgTraits<long long> {
-    typedef ValueLike ValueCategory;
-};
-#endif
-
-// ======================================================================
-// Unsigned integer types
-// ======================================================================
-
-/**
- * unsigned longs have value-like semantics.
- */
-template<>
-struct ArgTraits<unsigned long> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * unsigned ints have value-like semantics.
- */
-template<>
-struct ArgTraits<unsigned int> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * unsigned shorts have value-like semantics.
- */
-template<>
-struct ArgTraits<unsigned short> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * unsigned chars have value-like semantics.
- */
-template<>
-struct ArgTraits<unsigned char> {
-    typedef ValueLike ValueCategory;
-};
-
-// Microsoft implements size_t awkwardly. 
-#if defined(_MSC_VER) && defined(_M_X64)
-/**
- * size_ts have value-like semantics.
- */
-template<>
-struct ArgTraits<size_t> {
-    typedef ValueLike ValueCategory;
-};
-#endif
-
-
-#ifdef HAVE_LONG_LONG
-/**
- * unsigned long longs have value-like semantics.
- */
-template<>
-struct ArgTraits<unsigned long long> {
-    typedef ValueLike ValueCategory;
-};
-#endif
-
-// ======================================================================
-// Float types
-// ======================================================================
-
-/**
- * floats have value-like semantics.
- */
-template<>
-struct ArgTraits<float> {
-    typedef ValueLike ValueCategory;
-};
-
-/**
- * doubles have value-like semantics.
- */
-template<>
-struct ArgTraits<double> {
-    typedef ValueLike ValueCategory;
-};
-
-// ======================================================================
-// Other types
-// ======================================================================
-
-/**
- * bools have value-like semantics.
- */
-template<>
-struct ArgTraits<bool> {
-    typedef ValueLike ValueCategory;
-};
-
-
-/**
- * wchar_ts have value-like semantics.
- */
-#ifndef TCLAP_DONT_DECLARE_WCHAR_T_ARGTRAITS
-template<>
-struct ArgTraits<wchar_t> {
-    typedef ValueLike ValueCategory;
-};
-#endif
-
-/**
- * Strings have string like argument traits.
- */
 template<>
 struct ArgTraits<std::string> {
     typedef StringLike ValueCategory;

tests/Makefile.am

@@ -81,7 +81,8 @@ TESTS = test1.sh \
 		test79.sh \
 		test80.sh \
 		test81.sh \
-		test82.sh
+		test82.sh \
+		test83.sh
 
 EXTRA_DIST = $(TESTS) \
 			 test1.out \
@@ -165,6 +166,7 @@ EXTRA_DIST = $(TESTS) \
 			 test79.out \
 			 test80.out \
 			 test81.out \
-			 test82.out
+			 test82.out \
+			 test83.out
 
 CLEANFILES = tmp.out

tests/runtests.sh

@@ -2,7 +2,7 @@
 
 let "suc = 0"
 let "fail = 0"
-NUMTEST=82
+NUMTEST=83
 
 for (( tno = 1 ; $tno <= $NUMTEST ; tno = $tno + 1 )); do     
     ./testCheck.sh $tno

tests/test83.out

@@ -0,0 +1 @@
+1 2 3 

tests/test83.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+# this tests whether all required args are listed as
+# missing when no arguments are specified
+# failure  
+../examples/test24 -v "1 2 3" > tmp.out 2>&1
+
+if cmp -s tmp.out $srcdir/test84.out; then
+	exit 0
+else
+	exit 1
+fi
+