config-config no longer prepends train_ to task ids

This makes the "all" language hack easier to use.
When using this hack to achieve shared embeddings, it is no longer
possible to use src_lang and tgt_lang to distinguish tasks from each
other (because all tasks are just "all-all").
The iterate_tasks.py helper also supports using the task id as a
template variable. Having the real src-tgt as the task id, without any
useless train_ prefix makes file naming less painful.

mammoth/models/model.py

@@ -75,10 +75,10 @@ def forward(self, src, decoder_input, src_mask, metadata=None):
             return_embeddings=True,
         )
 
-        # encoder_output, alphas = self.attention_bridge(encoder_output, src_mask)
-        # if self.attention_bridge.is_fixed_length:
-        #     # turn off masking in the transformer decoder
-        #     src_mask = None
+        encoder_output, alphas = self.attention_bridge(encoder_output, src_mask)
+        if self.attention_bridge.is_fixed_length:
+            # turn off masking in the transformer decoder
+            src_mask = None
 
         retval = active_decoder(
             decoder_input,

tools/config_config.py

@@ -822,7 +822,7 @@ def _add_language_pair(opts, src_lang, tgt_lang, src_path, tgt_path, valid_src_p
     if 'tasks' not in opts.in_config[0]:
         opts.in_config[0]['tasks'] = dict()
     tasks_section = opts.in_config[0]['tasks']
-    key = f'train_{src_lang}-{tgt_lang}'
+    key = f'{src_lang}-{tgt_lang}'
     if key not in tasks_section:
         tasks_section[key] = dict()
     tasks_section[key]['src_tgt'] = f'{src_lang}-{tgt_lang}'

tools/iterate_tasks.py

@@ -16,7 +16,7 @@
     '--src',
     type=str,
     default=None,
-    help='Template for source file paths. Use varibles src_lang and tgt_lang.',
+    help='Template for source file paths. Use varibles src_lang, tgt_lang, and task_id.',
 )
 @click.option(
     '--output',
@@ -27,7 +27,7 @@
 @click.option(
     '--flag',
     is_flag=True,
-    help='Prefix with "--task_id". Implied by --src and --output.'
+    help='Prefix output with "--task_id". Implied by --src and --output.'
 )
 def main(config_path, match, src, output, flag):
     if src is not None or output is not None: