share code for pycat and loadpy

this make %pycat aware of URLs and %loadpy able to load file with the user not
having to write the py extension.

%loadpy is  still verifying that the loaded file as a
.py extension

IPython/core/magic.py

@@ -2276,20 +2276,21 b' Currently the magic system has the following functions:\\n"""'
         %loadpy myscript.py
         %loadpy http://www.example.com/myscript.py
         """
-        arg_s = unquote_filename(arg_s)
-        remote_url = arg_s.startswith(('http://', 'https://'))
-        local_url = not remote_url
-        if local_url and not arg_s.endswith('.py'):
+ 
+        fileorurl = self._get_file_or_url(arg_s)
+        contents = fileorurl['content']
+        local_url = fileorurl['local']
+        filename = fileorurl['filename']
+
+        if local_url and not filename.endswith('.py'):
             # Local files must be .py; for remote URLs it's possible that the
             # fetch URL doesn't have a .py in it (many servers have an opaque
             # URL, such as scipy-central.org).
             raise ValueError('%%loadpy only works with .py files: %s' % arg_s)
-        
-        # openpy takes care of finding the source encoding (per PEP 263)
-        if remote_url:
-            contents = openpy.read_py_url(arg_s, skip_encoding_cookie=True)
-        else:
-            contents = openpy.read_py_file(arg_s, skip_encoding_cookie=True)
+
+        if not contents : 
+            print "Error: no such file, variable or URL"
+            return
         
         self.set_next_input(contents)
 
@@ -3321,22 +3322,54 b' Defaulting color scheme to \'NoColor\'"""'
                 bkms[args[0]] = args[1]
         self.db['bookmarks'] = bkms
 
+    def _get_file_or_url(self, parameter_s=''):
+        """Try to find the content of a file or URL
+
+        return dict with key:
+        ====================
+        content : file or url content
+        filename : filename if local
+        local : (bool) true if local file
+
+        """
+
+        parameter_s = unquote_filename(parameter_s)
+        remote_url = parameter_s.startswith(('http://', 'https://'))
+
+        # openpy takes care of finding the source encoding (per PEP 263)
+        filename = None
+        if remote_url:
+            try :
+                cont = openpy.read_py_url(parameter_s, skip_encoding_cookie=True)
+            except IOError :
+                cont = None
+        else:
+            try:
+                filename = get_py_filename(parameter_s)
+                cont = file_read(filename)
+            except IOError:
+                try:
+                    cont = eval(parameter_s,self.user_ns)
+                except NameError:
+                    cont = None
+        return {'content': cont, 'filename':filename , 'local': not remote_url}
+
+
     def magic_pycat(self, parameter_s=''):
         """Show a syntax-highlighted file through a pager.
 
         This magic is similar to the cat utility, but it will assume the file
-        to be Python source and will show it with syntax highlighting. """
+        to be Python source and will show it with syntax highlighting.
 
-        try:
-            filename = get_py_filename(parameter_s)
-            cont = file_read(filename)
-        except IOError:
-            try:
-                cont = eval(parameter_s,self.user_ns)
-            except NameError:
-                cont = None
+        This magic command can either take a local filename or a url::
+
+        %pycat myscript.py
+        %pycat http://www.example.com/myscript.py
+        """
+
+        cont = self._get_file_or_url(parameter_s)['content']
         if cont is None:
-            print "Error: no such file or variable"
+            print "Error: no such file, variable or URL"
             return
 
         page.page(self.shell.pycolorize(cont))