Getting the name of something
Recently, I had the need to get an informative name from a range of Python objects for generating a useful error message. Where problems started was that these objects could include classes (new-style and old), functions, lambdas and built-in types. And here the logic started getting tricky.
- To get the name of the class of an object, you can use obj.__class__.__name__. But these could be the classes themselves.
- Likewise, the class of primitive types (int, float, str, etc.) is type, which is uninformative
- Functions have an attribute func_name, that could be useful
- Lambda's don't have any useful attribute for this at all, of course, because they are anonymous functions.
- Googling for a solution brings a whole host of overly complicated and incomplete answers.
The solution is easy: almost everything answers to __name__. So we can do this:
# variable is 'totype' type_name = None if hasattr (to_type, '__name__'): type_name = getattr (totype, '__name__') # lambdas and all others require name be explicitly supplied assert (type_name not in [None, '<lambda>']), \ "type validator requires type name for lambda"