https://github.com/frmdstryr/magicattr

A getattr and setattr that works on nested objects, lists, dicts, and any combination thereof without resorting to eval
https://github.com/frmdstryr/magicattr

python

Last synced: 3 months ago
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A getattr and setattr that works on nested objects, lists, dicts, and any combination thereof without resorting to eval

• Host: GitHub
• URL: https://github.com/frmdstryr/magicattr
• Owner: frmdstryr
• License: mit
• Created: 2018-06-04T20:02:09.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2022-02-18T22:22:01.000Z (almost 3 years ago)
• Last Synced: 2024-08-09T08:08:28.897Z (5 months ago)
• Topics: python
• Language: Python
• Size: 14.6 KB
• Stars: 16
• Watchers: 2
• Forks: 6
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Magicattr

[![status](https://github.com/frmdstryr/magicattr/actions/workflows/ci.yml/badge.svg)](https://github.com/frmdstryr/magicattr/actions)

[![codecov](https://codecov.io/gh/frmdstryr/magicattr/branch/master/graph/badge.svg)](https://codecov.io/gh/frmdstryr/magicattr)

[![Downloads](https://pepy.tech/badge/magicattr/month)](https://pepy.tech/project/magicattr)

A getattr and setattr that works on nested objects, lists,

dictionaries, and any combination thereof without resorting to eval.

It differs from getattr and setattr in that it retains the failure cause

instead of always raising an AttributeError.

### Example

Say we have a person class as follows:

```python

class Person:

    settings = {

        'autosave': True,

        'style': {

            'height': 30,

            'width': 200

        },

        'themes': ['light', 'dark']

    }

    def __init__(self, name, age, friends):

        self.name = name

        self.age = age

        self.friends = friends

bob = Person(name="Bob", age=31, friends=[])

jill = Person(name="Jill", age=29, friends=[bob])

jack = Person(name="Jack", age=28, friends=[bob, jill])

```

With magicattr we can do this

```python

# Nothing new

assert magicattr.get(bob, 'age') == 31

# Lists

assert magicattr.get(jill, 'friends[0].name') == 'Bob'

assert magicattr.get(jack, 'friends[-1].age') == 29

# Dict lookups

assert magicattr.get(jack, 'settings["style"]["width"]') == 200

# Combination of lookups

assert magicattr.get(jack, 'settings["themes"][-2]') == 'light'

assert magicattr.get(jack, 'friends[-1].settings["themes"][1]') == 'dark'

# Setattr

magicattr.set(bob, 'settings["style"]["width"]', 400)

assert magicattr.get(bob, 'settings["style"]["width"]') == 400

# Nested objects

magicattr.set(bob, 'friends', [jack, jill])

assert magicattr.get(jack, 'friends[0].friends[0]') == jack

magicattr.set(jill, 'friends[0].age', 32)

assert bob.age == 32

```

You can also delete like this too.

```python

# Deletion

magicattr.delete(jill, 'friends[0]')

assert len(jill.friends) == 0

magicattr.delete(jill, 'age')

assert not hasattr(jill, 'age')

magicattr.delete(bob, 'friends[0].age')

assert not hasattr(jack, 'age')

```

What if someone tries to mess with you?

```python

# Unsupported

with pytest.raises(NotImplementedError) as e:

    magicattr.get(bob, 'friends[0+1]')

with pytest.raises(SyntaxError) as e:

    magicattr.get(bob, 'friends[')

with pytest.raises(ValueError) as e:

    magicattr.get(bob, 'friends = [1,1]')

# Nice try, function calls are not allowed

with pytest.raises(ValueError):

    magicattr.get(bob, 'friends.pop(0)')

```

Did I miss anything? Let me know!

#### What it can't do?

Slicing, expressions, function calls, append/pop from lists, eval stuff, etc...

#### How does it work?

Parses the attr string into an ast node and manually evaluates it.

### Installing

`pip install magicattr`

### License

MIT

Hope it helps, cheers!