cmdopt2/parser: add a description parameter

cmdopt2/parser.cpp

@@ -7,6 +7,12 @@
 using cruft::cmdopt2::parser;
 
 
+///////////////////////////////////////////////////////////////////////////////
+parser::parser (char const *_description)
+    : m_description (_description)
+{ ; }
+
+
 ///////////////////////////////////////////////////////////////////////////////
 cruft::cmdopt2::positional_t&
 parser::add (positional_t const &arg)&
@@ -220,6 +226,7 @@ parser::parse (int const argc, const char *const *argv)
 void
 parser::usage (int argc, char const * const* argv, FILE *fp) const
 {
+    fmt::print (fp, FMT_STRING("{}\nUsage:"), m_description);
     if (argc > 0)
         fmt::print (fp, " {}", argv[0]);
 

cmdopt2/parser.hpp

@@ -17,6 +17,8 @@
 namespace cruft::cmdopt2 {
     class parser {
     public:
+        explicit parser (char const *desc);
+
         int parse [[nodiscard]] (int argc, char const* const* argv);
 
         positional_t& add (positional_t const&) &;
@@ -31,5 +33,7 @@ namespace cruft::cmdopt2 {
 
         std::vector<positional_t> m_positional;
         std::vector<keyword_t> m_keyword;
+
+        char const *m_description;
     };
 }

test/cmdopt2.cpp

@@ -80,7 +80,7 @@ test_combinations (cruft::TAP::logger &tap)
     bool verbose;
 
     using namespace cruft::cmdopt2;
-    parser p;
+    parser p ("test suite");
 
     p.add (keyword ("foo").flag ().flag ('f').bind (foo));
     p.add (keyword ("bar").bind (bar));
@@ -166,7 +166,7 @@ static void test_presence (cruft::TAP::logger &tap)
 
     using namespace cruft::cmdopt2;
 
-    parser p;
+    parser p ("test suite");
     p.add (keyword ("verbose").flag ().flag ('v').count (count));
     p.add (keyword ("present").flag ().flag ('p').present (present));
 
@@ -201,7 +201,7 @@ test_required (cruft::TAP::logger &tap)
 
     using namespace cruft::cmdopt2;
 
-    parser p;
+    parser p ("test suite");
     p.add (keyword ("y").flag ('y').required (true ).ignore ());
     p.add (keyword ("n").flag ('n').required (false).ignore ());