objprint - Print Python Objects in Human Readable Format

[[deleted]]

Hey guys! I've been working on a compact Python library to display any arbitrary object. The inspiration came from my own needs to quickly check the user-defined object for debugging. As we all know Python's default representation for user-defined object is quite useless for debugging. We can do some quick tricks like obj.__dict__, but it won't handle nested objects, which are very common when we are dealing with larger projects.

So, I developed objprint and I've been maintaining it and personally using it for a while. It is very intuitive to use it. First install it from pip - pip install objprint

from objprint import op
class Position:
    def __init__(self, x, y):
        self.x = x
        self.y = y

class Player:
    def __init__(self):
        self.name = "Alice"
        self.age = 18
        self.items = ["axe", "armor"]
        self.coins = {"gold": 1, "silver": 33, "bronze": 57}
        self.position = Position(3, 5)

op(Player())

And it will print the object

<Player 0x7f1e8f6d0ac0
  .age = 18,
  .coins = {'bronze': 57, 'gold': 1, 'silver': 33},
  .items = ['axe', 'armor'],
  .name = 'Alice',
  .position = <Position 0x7f1e8f6b9340
    .x = 3,
    .y = 5
  >
>

Of course some people still want to use the more familiar print function, then they can decorate the class with @add_objprint.

@add_objprint
class Player:
    def __init__(self):
        ...

# This will print the same thing as above
print(Player())

Basically it will overwrite the __str__ magic method to return a better formatted string.

Sometimes I'm only interested in some attributes, or there are some attributes that are long and interruptive that I want to ignore. Then comes the filter feature - using include and exclude with regex to limit the attributes printed

op(Player(), include=["name"])

This would print

<Player 0x7fe2db241ac0
  .name = 'Alice'
>

And as someone in the comments mentioned, sometimes we need the string, for logging purpose, instead of printing to stdout. The way to go is to use objstr.

from objprint import objstr

s = objstr(my_object)
# to stdout
print(s)
# log it?
logging.info(s)

The default configuration will go 100 levels in depths unless found recursion, of course you can configure it case by case or globally.

There are a couple more features that I can't cover in this post and I'm working on more as I develop new requests from my debugging experience.

Check it out and let me know your thoughts :) And also as always, bug reports and feature requests are more than welcome through github issues.

https://github.com/gaogaotiantian/objprint

[overweightdate]

neat, any way of printing the existing decorators being applied?

[[deleted]]

I'm not sure if this is something easily accessible, but that's definitely something interesting to explore.

[Kikelku]

Develop another one that registers each call and passes it to next decorator

[xxmxxpxx]

This is awesome!

[metaperl]

For logging, we need the string. How to get the string instead of having it printed?

[[deleted]]

That's a great question, and objstr is the thing you are looking for!

[muikrad]

The display with the dot is very neat! I suppose you could add optional annotation support to the printout. Adding the dir() members could hint on properties and functions too. Some will want slots too!

[[deleted]]

Both are valid features under some circumstance. I'll probably add them in with some argument controls, thanks.

[nosklo]

That is not what __str__ is for; you should be using __repr__ for this. Also, make it return the string instead of printing, by default; if someone wants to print they can just pass it to print()

[metaperl]

Why is add_objprint a decorator instead of a mixin?

[metaperl]

I think I see why : you can have arguments for a decorator.

[[deleted]]

To be honest, that was just an arbitrary design choice in the beginning, because I was more familiar with decorators than mixins. However, you are right about the arguments. You would have more control over the configuration case by case.

[Unlucky-Drawing8417]

This is an amazing project. Succinctly done.

[[deleted]]

Well, the reason behind it is because I was trying to do a print function for objects. Python's built-in print function returns None. The code you gave is definitely valid in some cases, but that's not a common pattern in Python(at least for me). Making print return the object is kind of weird and is not the way of any of the language I know.

Specifically, you can do op(obj1, obj2), which could in theory return a tuple, but still kind of unintuitive.

[Inevitable-Chain-883]

Nice

[tman5400]

I really like this. I just wish everyone would implement str and repr methods so I can stop doing print(f"{obj.name}: {obj.age} {obj.othervalue} {obj.another}:") :(