Method _decode_cfg_value

toolkit/yacs.py:405–440

Decodes a raw config value (e.g., from a yaml config files or command line argument) into a Python object. If the value is a dict, it will be interpreted as a new CfgNode. If the value is a str, it will be evaluated as literals. Otherwise it is returned as-i

(cls, value)

    @classmethod
    def _decode_cfg_value(cls, value):
        """
        Decodes a raw config value (e.g., from a yaml config files or command
        line argument) into a Python object.

        If the value is a dict, it will be interpreted as a new CfgNode.
        If the value is a str, it will be evaluated as literals.
        Otherwise it is returned as-is.
        """
        # Configs parsed from raw yaml will contain dictionary keys that need to be
        # converted to CfgNode objects
        if isinstance(value, dict):
            return cls(value)
        # All remaining processing is only applied to strings
        if not isinstance(value, str):
            return value
        # Try to interpret `value` as a:
        #   string, number, tuple, list, dict, boolean, or None
        try:
            value = literal_eval(value)
        # The following two excepts allow v to pass through when it represents a
        # string.
        #
        # Longer explanation:
        # The type of v is always a string (before calling literal_eval), but
        # sometimes it *represents* a string and other times a data structure, like
        # a list. In the case that v represents a string, what we got back from the
        # yaml parser is 'foo' *without quotes* (so, not '"foo"'). literal_eval is
        # ok with '"foo"', but will raise a ValueError if given 'foo'. In other
        # cases, like paths (v = 'foo/bar' and not v = '"foo/bar"'), literal_eval
        # will raise a SyntaxError.
        except ValueError:
            pass
        except SyntaxError:
            pass
        return value


load_cfg = (