Decode Complex Objects #23
Description
I can decode complex objects (like 'Extrinsic') in py-scalecodec like so:
def get_decoder_class(self, type_string: Union[str, dict]):
"""
Lookup and return a ScaleDecoder class for given `type_string`
Parameters
----------
type_string
Returns
-------
ScaleDecoder
"""
if type(type_string) is dict:
# Inner struct
decoder_class = type('InnerStruct', (self.get_decoder_class('Struct'),), {
'type_mapping': tuple(type_string.items())
})
decoder_class.runtime_config = self
return decoder_class
if type_string.strip() == '':
return None
if self.implements_scale_info is False:
type_string = self.convert_type_string(type_string)
decoder_class = self.type_registry.get('types', {}).get(type_string.lower(), None)
if not decoder_class:
# Type string containg subtype
if type_string[-1:] == '>':
# Extract sub types
type_parts = self.arrow_match_re.match(type_string)
if type_parts:
type_parts = type_parts.groups()
if type_parts:
# Create dynamic class for Part1<Part2> based on Part1 and set class variable Part2 as sub_type
base_class = self.type_registry.get('types', {}).get(type_parts[0].lower(), None)
if base_class:
decoder_class = type(type_string, (base_class,), {'sub_type': type_parts[1]})
# Custom tuples
elif type_string != '()' and type_string[0] == '(' and type_string[-1] == ')':
decoder_class = type(type_string, (self.get_decoder_class('tuple'),), {
'type_string': type_string
})
decoder_class.build_type_mapping()
elif type_string[0] == '[' and type_string[-1] == ']':
type_parts = self.bracket_match_re.match(type_string)
if type_parts:
type_parts = type_parts.groups()
if type_parts:
# Create dynamic class for e.g. [u8; 4] resulting in array of u8 with 4 elements
decoder_class = type(type_string, (self.get_decoder_class('FixedLengthArray'),), {
'sub_type': type_parts[0],
'element_count': int(type_parts[1])
})
if decoder_class:
# Attach RuntimeConfigurationObject to new class
decoder_class.runtime_config = self
return decoder_class