Registry / serialization / prettyprinter

prettyprinter

library0.18.0pypypi✓ verified 24d ago

PrettyPrinter is a Python library (version 0.18.0) that offers syntax-highlighting, declarative, and composable pretty printing for Python 3.5+ data structures. It aims to be a feature-rich alternative to Python's standard `pprint` module, providing improved readability, customizability, and integrations with other libraries. Its release cadence has been somewhat irregular, but the 0.18.0 version released in 2019 has been stable, suggesting a mature library.

serialization observability testing

pip install prettyprinter

github ↗package ↗

INSTALL

IMPORT

SIG · PRETTYPRINTER

prettyprinter

serializationpythonv0.18.0

Install

2.4s avg

Import

130ms

Disk

26MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.18.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.132s · 27.6MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 2.4s · import 0.128s · 28MB

26MB installed

● package 26MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

pprint

✓ from prettyprinter import pprint

✗ import pprint # This imports the standard library module

To use prettyprinter's main function, explicitly import `pprint` from `prettyprinter` to avoid conflict with the standard library's `pprint` module.

install_extras

✓ from prettyprinter import install_extras

Used for enabling integrations with shells (like IPython) or other third-party libraries (e.g., Django, NumPy, Requests).

register_pretty

✓ from prettyprinter import register_pretty, pretty_call

These functions are used when defining custom pretty-printing rules for your own Python types.

This quickstart demonstrates basic pretty-printing of a nested dictionary and how to define custom pretty-printing rules for your own classes using `@register_pretty`. It also notes how to enable shell integrations for a more persistent pretty-printing experience.

from prettyprinter import pprint, register_pretty, pretty_call # Basic pretty-printing of a nested dictionary data = { 'name': 'PrettyPrinter Example', 'details': { 'id': 12345, 'items': [ {'item_id': 'A1', 'value': 100.5, 'tags': ['new', 'sale']}, {'item_id': 'B2', 'value': 200, 'tags': ['old']}, {'item_id': 'C3', 'value': 50.75, 'tags': []} ], 'status': 'active' }, 'configs': [ {'key': 'timeout', 'value': 30}, {'key': 'retries', 'value': 5} ] } print('--- Standard print ---') print(data) print('\n--- PrettyPrinter output ---') pprint(data) # Custom pretty-printing for a user-defined class class MyObject: def __init__(self, name, values): self.name = name self.values = values @register_pretty(MyObject) def pretty_my_object(value, ctx): return pretty_call( ctx, MyObject, name=value.name, values=value.values ) my_instance = MyObject('CustomItem', [{'x': 1, 'y': 2}, {'z': 3}]) print('\n--- Custom object pretty-printing ---') pprint(my_instance) # To enable shell integration (e.g., for `ipython` or default python shell): # from prettyprinter import install_extras # install_extras(['ipython']) # or ['python'] # {'a': 1, 'b': 2} # will now be pretty-printed in the shell

Debug

Known issues

breakingThe default behavior for dictionary key sorting changed in version 0.8.0. Previously, keys were sorted like in the standard library's `pprint` module. Now, they default to insertion order (for CPython 3.6+). To revert to sorted keys, use the `sort_dict_keys` argument in `pprint` or configure it in `PrettyContext` for custom printers.

fix

If sorted dictionary keys are required, explicitly pass `sort_dict_keys=True` to `pprint()` or `pformat()`, or set this option in your custom `PrettyContext`.

affects: 0.8.0 and later

gotchaThere are two distinct Python libraries with similar names: the built-in `pprint` module and the external `prettyprinter` library. Users often confuse the two. `prettyprinter` offers enhanced features like syntax highlighting, a more flexible API, and extensibility, which the standard library module does not.

fix

Always explicitly `from prettyprinter import pprint` to ensure you are using the external library. Avoid `import pprint` if you intend to use `prettyprinter`'s features, as it will import the standard library module.

affects: All versions

gotchaFor `prettyprinter` to automatically format output in Python shells (like IPython or the default Python REPL) or for it to pretty-print types from other popular libraries (e.g., `dataclasses`, `attrs`, `django`), you must explicitly call `install_extras()`. Without this, only basic types will be pretty-printed, and shell integration will not occur.

fix

Call `from prettyprinter import install_extras; install_extras(['python'])` for the default shell or `install_extras(['ipython'])` for IPython. You can also specify other libraries like `install_extras(include=['dataclasses', 'requests'])`. For persistent shell integration, consider setting the `PYTHONSTARTUP` environment variable.

affects: All versions

deprecatedWhen defining custom pretty printers, the `PrettyContext.set` method was deprecated in favor of `PrettyContext.assoc`. While `set` might still work in older versions, `assoc` is the recommended and clearer method for modifying context values.

fix

Update your custom pretty printer definitions to use `ctx.assoc(...)` instead of `ctx.set(...)` for context manipulation.

affects: 0.8.0 and later

gotchaWhen trying to pretty-print custom objects, simply defining a `__repr__` method on your class might not fully leverage `prettyprinter`'s capabilities or might even be overridden by `prettyprinter`'s default handling for certain base types. The library's declarative approach provides a more robust way.

fix

For optimal and consistent pretty-printing of custom types, use `prettyprinter.register_pretty` with a dedicated pretty printer function, combined with `pretty_call`, rather than solely relying on `__repr__`.

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'prettyprinter'

The 'prettyprinter' library has not been installed in the current Python environment.

fix

Install the package using pip: `pip install prettyprinter`

NameError: name 'pprint' is not defined

The 'pprint' function from the 'prettyprinter' library was used without being explicitly imported or qualified.

fix

Import the 'pprint' function: `from prettyprinter import pprint` or use `import prettyprinter` and then `prettyprinter.pprint(...)`

AttributeError: module 'pprint' has no attribute 'install_extras'

The user attempted to call `install_extras` on Python's standard library `pprint` module, mistaking it for the `prettyprinter` library. `install_extras` is a function specific to the `prettyprinter` library.

fix

Ensure you are importing `install_extras` from the `prettyprinter` library: `from prettyprinter import install_extras`

AttributeError: module 'pprint' has no attribute 'register_pretty'

The user attempted to use the `@register_pretty` decorator (or function) from the standard library `pprint` module, mistaking it for the `prettyprinter` library. `register_pretty` is a feature of the `prettyprinter` library for defining custom pretty printers.

fix

Ensure you are importing `register_pretty` from the `prettyprinter` library: `from prettyprinter import register_pretty`

Upgrade

Version history

0.18.0latest on PyPI · released Jun 22, 2019

Audit

Dependencies

No dependency data recorded yet.

Agent activity

21 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/tommikaikkonen/prettyprinter ↗

packagehttps://pypi.org/project/prettyprinter/ ↗