Validation and behavior in case of problems#

izulu may trigger native Python exceptions on invalid data during validation process. By default you should expect following ones

TypeError: argument constraints issues
ValueError: template and formatting issues

Some exceptions are raised from original exception (e.g. template formatting issues), so you can check e.__cause__ and traceback output for details.

The validation behavior depends on the set of enabled toggles. Changing toggle set may cause different and raw exceptions being raised. Read and understand “Toggles” section to predict and experiment with different situations and behaviours.

izulu has 2 validation stages:

class definition stage

validation is made during error class definition

# when you import error module
from izulu import root

# when you import error from module
from izulu.root import Error

# when you interactively define new error classes
class MyError(Error):
    pass

class attributes __template__ and __toggles__ are validated

class MyError(Error):
    __template__ = "Hello {}"

# ValueError: Field names can't be empty

runtime stage

validation is made during error instantiation
```
root.Error()
```

kwargs are validated according to enabled toggles

class MyError(Error):
    __template__ = "Hello {name}"
    name: str

MyError()
# TypeError: Missing arguments: 'name'