Package konval :: Module typeval :: Class ToType

Class ToType

                 object --+    
                          |    
basevalidator.BaseValidator --+
                              |
                             ToType

Known Subclasses:

Convert a value to a given type.

This is largely syntactic sugar: It will actually accept any callable as an argument, but is intended for use with class constructors. You could use raw types and classes, but this throws much nicer error messages. Conversion is done by simply passing a value to the parameter callable.

Instance Methods

[hide private]

__init__(self, to_type, type_name=None)
Class c'tor, accepting a type.

source code

make_conversion_error_msg(self, bad_val, err)
Generate an appropriate error message for type conversion problem.

source code

convert_value(self, value)
Transform a value to the desired form.

source code

Inherited from basevalidator.BaseValidator: __call__, convert, make_validation_error_msg, raise_conversion_error, raise_validation_error, validate, validate_value

Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __sizeof__, __str__, __subclasshook__

Properties

[hide private]

Inherited from object: __class__

Method Details

[hide private]

init(self, to_type, type_name=None)
(Constructor)

source code

Class c'tor, accepting a type.

For example:

>>> v = ToType(int, type_name='an integer')
>>> v(1)
1
>>> v(2.3)
2
>>> v('foo')
Traceback (most recent call last):
...
ValueError: can't convert 'foo' to an integer
>>> v = ToType(float)
>>> v('foo')
Traceback (most recent call last):
...
ValueError: can't convert 'foo' to float

Parameters:

to_type (callable) - A class constructor (old or new style), built-in type, or function that can be called to convert a type and will throw if it fails.
type_name (string) - A name for the type produced. If not supplied, it will be extracted from to_type if possible.

Overrides: object.__init__

make_conversion_error_msg(self, bad_val, err)

source code

Generate an appropriate error message for type conversion problem.

Overrides: basevalidator.BaseValidator.make_conversion_error_msg

convert_value(self, value)

source code

Transform a value to the desired form.

This is the workhorse method that is called by convert to transform passed values. As such, errors are signalled by throwing a meaningful exception. This is one of the obvious and easiest places to customize behaviour by overriding in a subclass.

Parameters:

value - value to be transformed

Returns:

the transformed value

Overrides: basevalidator.BaseValidator.convert_value

(inherited documentation)

Class ToType

__init__(self, to_type, type_name=None) (Constructor)

make_conversion_error_msg(self, bad_val, err)

convert_value(self, value)

init(self, to_type, type_name=None)
(Constructor)