hbutils.model.repr

Representation formatting utilities for model-like objects.

This module provides a small but flexible utility for generating consistent __repr__ output across custom classes. It is designed to simplify the construction of informative object representations while allowing conditional display of attributes.

The module contains the following public function:

Example:

>>> from hbutils.model.repr import get_repr_info
>>> class Point:
...     def __init__(self, x, y=None):
...         self._x = x
...         self._y = y
...     def __repr__(self):
...         return get_repr_info(
...             cls=self.__class__,
...             args=[
...                 ('y', (lambda: self._y, lambda: self._y is not None)),
...                 ('x', lambda: self._x),
...             ]
...         )
...
>>> Point(3, 4)
<Point y: 4, x: 3>
>>> Point(3)
<Point x: 3>

Note

This utility does not access object state directly; all data access is done through the provided callables. This makes it safe to use for lazily computed properties or sensitive attributes.

__all__

hbutils.model.repr.__all__ = ['get_repr_info']

Built-in mutable sequence.

If no argument is given, the constructor creates a new empty list. The argument must be an iterable if specified.

get_repr_info

hbutils.model.repr.get_repr_info(cls: type, args: Sequence[Tuple[str, Callable[[], Any]] | Tuple[str, Tuple[Callable[[], Any], Callable[[], bool]]] | Tuple[str, Callable[[], Any], Callable[[], bool]]]) → str[source]

Get representation information for object.

This function generates a formatted string representation of an object based on the provided class type and argument information. It can be used in __repr__ methods to create consistent and informative object representations.

Parameters:

  • cls (type) – The class type of the object to represent.

  • args (Sequence[Union[Tuple[str, Callable[[], Any]], Tuple[str, Tuple[Callable[[], Any], Callable[[], bool]]], Tuple[str, Callable[[], Any], Callable[[], bool]]]]) –

    A sequence of tuples describing how each field should be shown. Each item must be one of the following forms:

    • (name, data_func): Always display name with value from data_func.

    • (name, (data_func, present_func)): Display only if present_func is True.

    • (name, data_func, present_func): Equivalent to the previous form.

    Where:

    • name (str): The name of the field to display.

    • data_func (Callable): Callable returning the value to display.

    • present_func (Callable): Callable returning True if the field should be displayed.

Returns:

A formatted representation string in the format <ClassName arg1: value1, arg2: value2>. If no fields are displayed, the format is <ClassName>.

Return type:

str

Raises:

  • ValueError – If a tuple’s length is not 2 or 3.

  • TypeError – If an argument item is not a tuple.

Example:

>>> from hbutils.model.repr import get_repr_info
>>> class Sum:
...     def __init__(self, a, b):
...         self.__a = a
...         self.__b = b
...     def __repr__(self):
...         return get_repr_info(
...             cls=self.__class__,
...             args=[
...                 ('b', lambda: self.__b, lambda: self.__b is not None),
...                 ('a', lambda: self.__a),
...             ]
...         )
...
>>> Sum(1, 2)
<Sum b: 2, a: 1>
>>> Sum(1, None)
<Sum a: 1>
>>> Sum(None, None)
<Sum a: None>