Is there a way to get a type object, given the name of that type? So, for example:
get_type('str') -> str
I am building a dict mapping various cases to a class which should be instantiated to handle them. It seems overkill to import everything and risk circular imports. So I thought I could specify them with strings, and look up the type at point of use. But how do I look up the type?
It seems unlikely that this hasn't been asked before, but I've searched and not found it.
You can get the builtin types by checking attribute on the builtins module using getattr:
In [665]: import builtins
In [666]: def get_type(type_name):
...: try:
...: return getattr(builtins, type_name)
...: except AttributeError:
...: return None
...:
In [667]: get_type('str')
Out[667]: str
In [668]: get_type('list')
Out[668]: list
In [669]: get_type('dict')
Out[669]: dict
FWIW, you can replace the AttributeError catching with passing the third parameter to getattr which acts as a default when attribute is missing (thanks @Error - Syntactical Remorse for the reminder):
def get_type(type_name):
return getattr(builtins, type_name, None)
For handling custom types, you can peek into the globals dict:
In [670]: def get_type(type_name):
...: try:
...: return getattr(builtins, type_name)
...: except AttributeError:
...: try:
...: obj = globals()[type_name]
...: except KeyError:
...: return None
...: return repr(obj) if isinstance(obj, type) else None
...:
In [671]: class B:
...: pass
...:
In [672]: get_type('B')
Out[672]: "<class '__main__.B'>"
In [673]: get_type('C') is None
Out[673]: True