Crash when 'name' is not a hashable type.

[max-kamps]

When a rules's name is not a hashable type (e.g. a list), like in this rule:

Root:
	name+=ID[','] ;

process_node crashes ungracefully:

  File "/usr/bin/textx", line 11, in <module>
    sys.exit(textx())
  File "/usr/lib/python3.6/site-packages/textx/commands/console.py", line 51, in textx
    model = metamodel.model_from_file(args.model, debug=args.d)
  File "/usr/lib/python3.6/site-packages/textx/metamodel.py", line 465, in model_from_file
    encoding, debug=debug)
  File "/usr/lib/python3.6/site-packages/textx/model.py", line 168, in get_model_from_file
    debug=debug)
  File "/usr/lib/python3.6/site-packages/textx/model.py", line 194, in get_model_from_str
    model = parse_tree_to_objgraph(self, self.parse_tree[0])
  File "/usr/lib/python3.6/site-packages/textx/model.py", line 520, in parse_tree_to_objgraph
    model = process_node(parse_tree)
  File "/usr/lib/python3.6/site-packages/textx/model.py", line 333, in process_node
    parser._instances[id(inst.__class__)][inst.name] = inst
TypeError: unhashable type: 'list'

[igordejanovic]

Attributes called name are treated in a special way. They are used for reference auto-resolving feature. So, yes, name must be of a hashable type. I'll add a note in the docs.

[igordejanovic]

As a side note, if you don't have a strict requirement for name to be a list, the idiomatic way to use this kind of identifier would be to create your match rule for a list of IDs and use that instead.

Root: name=MyID;
MyID: ID+[','];

Match rules by default return matched string (if you do not use match filters) so no problem with name lookups.

[max-kamps]

Oh no, I was just surprised that it crashed instead of reporting that the metamodel was not OK.
I still think it would be better to check for stuff like this while parsing the metamodel, but I understand if that is too complex with the current setup. Haven't bothered to look into the code yet.

[igordejanovic]

Yes. I agree. Better error reporting would be nice. I'll look into it when find some time.