pyproprop 0.0.3

What is pyproprop?

Do you often find yourself writing classes with properties such as:

from some_other_module import DefaultObject, some_type

class ExampleClass:

    def __init__(self,
                 type_checked_value,
                 bounded_numeric_value,
                 specific_length_sequence_value,
                 obj_with_method_applied_value,
                 ):
        self.type_check_attr = type_checked_value
        self.bounded_numeric_attr = bounded_numeric_value
        self.specific_length_sequence_attr = specific_length_sequence_value
        self.obj_with_method_applied_attr = obj_with_method_applied_value
        self.instantiate_default_if_none_attr = None

    @property
    def type_checked_attr(self):
        return self._type_checked_attr

    @type_checked_attr.setter
    def type_checked_attr(self, val):
        if not isinstance(val, some_type):
            msg = "`type_checked_attr` must be of `some_type`"
            raise TypeError(msg)
        self._type_checked_attr = val

    @property
    def bounded_numeric_attr(self):
        return self._bounded_numeric_attr

    @bounded_numeric_attr.setter
    def bounded_numeric_attr(self, val):
        val = float(val)
        lower_bound = -1.0
        upper_bound = 2.5
        if val < lower_bound:
            msg = f"`bounded_numeric_attr` must be greater than {lower_bound}"
            raise ValueError(msg)
        if val >= upper_bound:
            msg = (f"`bounded_numeric_attr` must be less than or equal to "
                   f"{upper_bound}.")
            raise ValueError(msg)
        self._type_checked_attr = val

    @property
    def specific_length_sequence_attr(self):
        return self._specific_length_sequence_attr

    @specific_length_sequence_attr.setter
    def specific_length_sequence_attr(self, val):
        if len(val) != 2:
            msg = "`specific_length_sequence` must be an iterable of length 2."
            raise ValueError(msg)
        self._specific_length_sequence_attr = val

    @property
    def obj_with_method_applied_value(self):
        return self._obj_with_method_applied_value

    @obj_with_method_applied_value.setter
    def obj_with_method_applied_value(self, val):
        val = str(val)
        self._obj_with_method_applied_value = val.title()

    @property
    def instantiate_default_if_none_attr(self):
        return self._instantiate_default_if_none_attr

    @instantiate_default_if_none_attr.setter
    def instantiate_default_if_none_attr(self, val):
        if val is None:
            val = DefaultObject()
        self._instantiate_default_if_none_attr = val

With pyproprop all of this boilerplate can be removed and instead the exact same class can be rewritten as:

from pyproprop import processed_property
from some_other_module import DefaultObject, some_type

class ExampleClass:

    type_checked_attr = processed_property(
        "type_checked_attr",
        description="property with enforced type of `some_type`",
        type=some_type,
    )
    bounded_numeric_attr = processed_property(
        "bounded_numeric_attr",
        description="numerical attribute with upper and lower bounds"
        type=float,
        cast=True,
        min=-1.0,
        max=2.5,
    )
    specific_length_sequence_attr = processed_property(
        "specific_length_sequence_attr",
        description="sequence of length exactly 2",
        len=2,
    )
    obj_with_method_applied_attr = processed_property(
        "obj_with_method_applied_attr",
        description="sting formatted to use title case"
        type=str,
        cast=True,
        method="title",
    )
    instantiate_default_if_none_attr = processed_property(
        "instantiate_default_if_none_attr",
        default=DefaultObject,
    )

    def __init__(self,
                 type_checked_value,
                 bounded_numeric_value,
                 specific_length_sequence_value,
                 obj_with_method_applied_value,
                 ):
        self.type_check_attr = type_checked_value
        self.bounded_numeric_attr = bounded_numeric_value
        self.specific_length_sequence_attr = specific_length_sequence_value
        self.obj_with_method_applied_attr = obj_with_method_applied_value
        self.instantiate_default_if_none_attr = None

Installation

The easiest way to install pyproprop is using the [Anaconda Python distribution](https://www.anaconda.com/what-is-anaconda/) and its included Conda package management system. To install pyproprop and its required dependencies, enter the following command at a command prompt:

conda install pyproprop

To install using pip, enter the following command at a command prompt:

pip install pyproprop

For more information, refer to the [installation documentation](https://pyproprop.readthedocs.io/en/latest/installation.html).

Contribute

• Issue Tracker: github.com/brocksam/pyproprop/issues

• Source Code: github.com/brocksam/pyproprop

License

This project is licensed under the terms of the MIT license.