IGN:...

src/calibre/customize/__init__.py

@@ -220,4 +220,6 @@ class MetadataWriterPlugin(Plugin):
 
         '''
         pass
-    
+
+
+   

src/calibre/customize/conversion.py

@@ -0,0 +1,72 @@
+'''
+Defines the plugin sytem for conversions.
+'''
+import re
+
+from calibre.customize import Plugin
+
+
+class ConversionOption(object):
+    
+    '''
+    Class representing conversion options
+    '''
+    
+    def __init__(self, name=None, default=None, help=None, long_switch=None, 
+                 short_switch=None, choices=None, gui_label=None, 
+                 category=None):
+        self.name = name
+        self.default = default
+        self.help = help
+        self.long_switch = long_switch
+        self.short_switch = short_switch
+        self.choices = choices
+        self.gui_label = gui_label
+        self.category = category
+        
+        self.validate_parameters()
+        
+    def validate_parameters(self):
+        '''
+        Validate the parameters passed to :method:`__init__`.
+        '''
+        if re.match(r'[a-zA-Z_]([a-zA-Z0-9_])*', self.name) is None:
+            raise ValueError(self.name + ' is not a valid Python identifier')
+        if not (isinstance(self.default, (int, float, str, unicode)) or \
+            self.default is None):
+            raise ValueError(unicode(self.default) + 
+                             ' is not a string or a number')
+        if not self.help:
+            raise ValueError('You must set the help text')      
+
+class ConversionPlugin(Plugin):
+    
+    '''
+    The base class for all conversion related plugins.
+    '''
+    #: List of options
+    #: Each option must be a dictionary. The dictionary can contain several
+    #: keys defining the option. The ones marked by a * are required, the rest
+    #: are optional. The keys are::
+    #:
+    #:    *'name'        : A valid python identifier.
+    #:    *'default'     : The default value for this option.
+    #:    *'help'        : 
+    #:    'short_switch' : A suggestion for a short form of the command line
+    #:                     switch (for example if name is 'title', this 
+    #:                     could be 't'). It is only used if no prior
+    #:                     conversion plugin has claimed it. 
+    options = []
+    
+    type = _('Conversion')
+    can_be_disabled = False
+    supported_platforms = ['windows', 'osx', 'linux']
+    
+
+class InputFormatPlugin(ConversionPlugin):
+    
+    #: Set of file types for which this plugin should be run
+    #: For example: ``set(['lit', 'mobi', 'prc'])``
+    file_types     = set([])
+    
+