enhance support for model switching and editing

- Error checks for invalid model
- Add !del_model command to invoke.py
- Add del_model() method to model_cache
- Autocompleter kept in sync with model addition/subtraction.

ldm/invoke/args.py

@@ -519,7 +519,7 @@ class Args(object):
             formatter_class=ArgFormatter,
             description=
             """
-            *Image generation:*
+            *Image generation*
                  invoke> a fantastic alien landscape -W576 -H512 -s60 -n4
 
             *postprocessing*
@@ -534,6 +534,13 @@ class Args(object):
             !history lists all the commands issued during the current session.
 
             !NN retrieves the NNth command from the history
+
+            *Model manipulation*
+            !models                                 -- list models in configs/models.yaml
+            !switch <model_name>                    -- switch to model named <model_name>
+            !import_model path/to/weights/file.ckpt -- adds a model to your config
+            !edit_model <model_name>                -- edit a model's description
+            !del_model <model_name>                 -- delete a model
             """
         )
         render_group     = parser.add_argument_group('General rendering')

ldm/invoke/model_cache.py

@@ -73,7 +73,8 @@ class ModelCache(object):
             except Exception as e:
                 print(f'** model {model_name} could not be loaded: {str(e)}')
                 print(f'** restoring {self.current_model}')
-                return self.get_model(self.current_model)
+                self.get_model(self.current_model)
+                return None
         
         self.current_model = model_name
         self._push_newest_model(model_name)
@@ -121,6 +122,16 @@ class ModelCache(object):
             else:
                 print(line)
 
+    def del_model(self, model_name:str) ->str:
+        '''
+        Delete the named model and return the YAML
+        '''
+        omega = self.config
+        del omega[model_name]
+        if model_name in self.stack:
+            self.stack.remove(model_name)
+        return OmegaConf.to_yaml(omega)
+
     def add_model(self, model_name:str, model_attributes:dict, clobber=False) ->str:
         '''
         Update the named model with a dictionary of attributes. Will fail with an

ldm/invoke/readline.py

@@ -53,11 +53,12 @@ COMMANDS = (
     '--log_tokenization','-t',
     '--hires_fix',
     '!fix','!fetch','!history','!search','!clear',
-    '!models','!switch','!import_model','!edit_model'
+    '!models','!switch','!import_model','!edit_model','!del_model',
     )
 MODEL_COMMANDS = (
     '!switch',
     '!edit_model',
+    '!del_model',
     )
 WEIGHT_COMMANDS = (
     '!import_model',
@@ -205,9 +206,24 @@ class Completer(object):
         pydoc.pager('\n'.join(lines))
 
     def set_line(self,line)->None:
+        '''
+        Set the default string displayed in the next line of input.
+        '''
         self.linebuffer = line
         readline.redisplay()
 
+    def add_model(self,model_name:str)->None:
+        '''
+        add a model name to the completion list
+        '''
+        self.models.append(model_name)
+
+    def del_model(self,model_name:str)->None:
+        '''
+        removes a model name from the completion list
+        '''
+        self.models.remove(model_name)
+
     def _seed_completions(self, text, state):
         m = re.search('(-S\s?|--seed[=\s]?)(\d*)',text)
         if m: