Implementation of Rust's Result- and Option-Type in Python.
Can be used to mimic similar behaviour as Rust to propagate Exceptions to the caller instead of handling them in the method itself and use default values if there is an Error or the Option is None.
from dataclasses import dataclass
import tomllib
from results import Err, Ok, Result
@dataclass
class Config:
debug: bool
value: int
def parse_config_from_toml_string(config_str: str) -> Result[Config, Exception]:
"""Takes in a TOML string and returns a Result[Config, Exception]"""
try:
data = tomllib.loads(config_str)
except tomllib.TOMLDecodeError as e:
return Err(e)
tool = data.get("tool")
if not tool:
return Err(ValueError("No configuration for tool in config."))
try:
config = Config(**tool)
except TypeError as e:
return Err(e)
return Ok(config)
if __name__ == "__main__":
valid_config_str = """[tool]
debug = true
value = 10"""
invalid_config_str = """[wrong]
debug = true
value = 10"""
valid_config_result = parse_config_from_toml_string(config_str=valid_config_str)
invalid_config_result = parse_config_from_toml_string(config_str=invalid_config_str)
# You can match on the result
match valid_config_result:
case Err(err):
print(err)
case Ok(config):
print(config)
# Use a default for the config if Err
print(invalid_config_result.unwrap_or(Config(debug=False, value=2)))