reflect new box2d<double>from_bbox() function in python, and add a new value_error class to represent parsing errors (TODO: translate in python to ValueError and throw from other parsers like expression and color)

bindings/python/mapnik_envelope.cpp

@@ -26,6 +26,7 @@
 
 // mapnik
 #include <mapnik/box2d.hpp>
+#include <mapnik/value_error.hpp>
 
 using mapnik::coord;
 using mapnik::box2d;
@@ -40,6 +41,22 @@ struct envelope_pickle_suite : boost::python::pickle_suite
     }
 };
 
+box2d<double> from_string(std::string const& s)
+{
+    box2d<double> bbox;
+    bool success = bbox.from_string(s);
+    if (success)
+    {
+        return bbox;
+    }
+    else
+    {
+        std::stringstream ss;
+        ss << "Could not parse bbox from string: '" << s << "'";
+        throw mapnik::value_error(ss.str());
+    }
+}
+
 //define overloads here
 void (box2d<double>::*width_p1)(double) = &box2d<double>::width;
 double (box2d<double>::*width_p2)() const = &box2d<double>::width;
@@ -80,6 +97,8 @@ void export_envelope()
         .def(init<const coord<double,2>&, const coord<double,2>&>(
                  (arg("ll"),arg("ur")),
                  "Equivalent to Box2d(ll.x, ll.y, ur.x, ur.y).\n"))
+        .def("from_string",from_string)
+        .staticmethod("from_string")
         .add_property("minx", &box2d<double>::minx, 
                       "X coordinate for the lower left corner")
         .add_property("miny", &box2d<double>::miny, 

include/mapnik/value_error.hpp

@@ -0,0 +1,57 @@
+/*****************************************************************************
+ * 
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2006 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_VALUE_ERROR_INCLUDED
+#define MAPNIK_VALUE_ERROR_INCLUDED
+
+#include <iostream>
+#include <sstream>
+
+namespace mapnik {
+
+class value_error : public std::exception
+{
+public:
+    value_error() {}
+
+    value_error( const std::string & what ) :
+        what_( what )
+    {
+    }
+    virtual ~value_error() throw() {};
+
+    virtual const char * what() const throw()
+    {
+        return what_.c_str();    
+    }
+
+    void append_context(const std::string & ctx) const
+    {
+        what_ += " " + ctx;
+    }
+
+protected:
+    mutable std::string what_;
+};
+}
+
+#endif // MAPNIK_VALUE_ERROR_INCLUDED