A Python module for decorators, wrappers and monkey patching.

Related tags

Miscellaneouswrapt
Overview

wrapt

Travis Appveyor Coveralls PyPI

The aim of the wrapt module is to provide a transparent object proxy for Python, which can be used as the basis for the construction of function wrappers and decorator functions.

The wrapt module focuses very much on correctness. It therefore goes way beyond existing mechanisms such as functools.wraps() to ensure that decorators preserve introspectability, signatures, type checking abilities etc. The decorators that can be constructed using this module will work in far more scenarios than typical decorators and provide more predictable and consistent behaviour.

To ensure that the overhead is as minimal as possible, a C extension module is used for performance critical components. An automatic fallback to a pure Python implementation is also provided where a target system does not have a compiler to allow the C extension to be compiled.

Documentation

For further information on the wrapt module see:

Quick Start

To implement your decorator you need to first define a wrapper function. This will be called each time a decorated function is called. The wrapper function needs to take four positional arguments:

  • wrapped - The wrapped function which in turns needs to be called by your wrapper function.
  • instance - The object to which the wrapped function was bound when it was called.
  • args - The list of positional arguments supplied when the decorated function was called.
  • kwargs - The dictionary of keyword arguments supplied when the decorated function was called.

The wrapper function would do whatever it needs to, but would usually in turn call the wrapped function that is passed in via the wrapped argument.

The decorator @wrapt.decorator then needs to be applied to the wrapper function to convert it into a decorator which can in turn be applied to other functions.

import wrapt

@wrapt.decorator
def pass_through(wrapped, instance, args, kwargs):
    return wrapped(*args, **kwargs)

@pass_through
def function():
    pass

If you wish to implement a decorator which accepts arguments, then wrap the definition of the decorator in a function closure. Any arguments supplied to the outer function when the decorator is applied, will be available to the inner wrapper when the wrapped function is called.

import wrapt

def with_arguments(myarg1, myarg2):
    @wrapt.decorator
    def wrapper(wrapped, instance, args, kwargs):
        return wrapped(*args, **kwargs)
    return wrapper

@with_arguments(1, 2)
def function():
    pass

When applied to a normal function or static method, the wrapper function when called will be passed None as the instance argument.

When applied to an instance method, the wrapper function when called will be passed the instance of the class the method is being called on as the instance argument. This will be the case even when the instance method was called explicitly via the class and the instance passed as the first argument. That is, the instance will never be passed as part of args.

When applied to a class method, the wrapper function when called will be passed the class type as the instance argument.

When applied to a class, the wrapper function when called will be passed None as the instance argument. The wrapped argument in this case will be the class.

The above rules can be summarised with the following example.

import inspect

@wrapt.decorator
def universal(wrapped, instance, args, kwargs):
    if instance is None:
        if inspect.isclass(wrapped):
            # Decorator was applied to a class.
            return wrapped(*args, **kwargs)
        else:
            # Decorator was applied to a function or staticmethod.
            return wrapped(*args, **kwargs)
    else:
        if inspect.isclass(instance):
            # Decorator was applied to a classmethod.
            return wrapped(*args, **kwargs)
        else:
            # Decorator was applied to an instancemethod.
            return wrapped(*args, **kwargs)

Using these checks it is therefore possible to create a universal decorator that can be applied in all situations. It is no longer necessary to create different variants of decorators for normal functions and instance methods, or use additional wrappers to convert a function decorator into one that will work for instance methods.

In all cases, the wrapped function passed to the wrapper function is called in the same way, with args and kwargs being passed. The instance argument doesn't need to be used in calling the wrapped function.

Repository

Full source code for the wrapt module, including documentation files and unit tests, can be obtained from github.

Owner
Graham Dumpleton
Graham Dumpleton
Magenta: Music and Art Generation with Machine Intelligence

Magenta is a research project exploring the role of machine learning in the process of creating art and music. Primarily this involves developing new

Magenta 18.1k Jan 05, 2023
A python script to make leaderboards using a CSV with the runners name, IDs and Flag Emojis

SrcLbMaker A python script to make speedrun.com global leaderboards. Installation You need python 3.6 or higher. First, go to the folder where you wan

2 Jul 25, 2022
ViberExport - Export messages from Viber messenger using viber.db file

📲 ViberExport Export messages from Viber messenger using viber.db file ⚡ Usage:

7 Nov 23, 2022
Python 101 Forever

🚀 Python 101 Forever 🚀 Official Python 101 Forever GitHub repository. START HERE - CHECK README SUBSCRIBE FOR UPDATES HERE Sponsors Contac

Hack Bulgaria 58 Nov 30, 2022
Enjoy Discords Unlimited Storage

Discord Storage V.3.5 (Beta) Made by BoKa Enjoy Discords free and unlimited storage... Prepare: Clone this from Github, make sure there either a folde

0 Dec 16, 2021
Python communism - A module for initiating the communist revolution in each of our python modules

Python communist revolution A man once said to abolish the classes or something

758 Jan 03, 2023
BasicVSR++ function for VapourSynth

BasicVSR++ BasicVSR++: Improving Video Super-Resolution with Enhanced Propagation and Alignment Ported from https://github.com/open-mmlab/mmediting De

Holy Wu 34 Nov 28, 2022
Ballistic calculator for Airsoft

Ballistic-calculator-for-Airsoft 用于Airsoft的弹道计算器 This is a ballistic calculator for airsoft gun. To calculate your airsoft gun's ballistic, you should

3 Jan 20, 2022
Remove Sheet Protection from .xlsx files. Easily.

🔓 Excel Sheet Unlocker Remove sheet protection from .xlsx files. How to use Run Run the script/packaged executable from the command line. Universal u

Daniel 3 Nov 16, 2022
Collection of functions for working with interlaced content in VapourSynth.

vsfieldkit Collection of functions for working with interlaced content in VapourSynth. It does not have any hard dependencies outside of VapourSynth.

Justin Turner Arthur 11 May 27, 2022
Structural basis for solubility in protein expression systems

Structural basis for solubility in protein expression systems Large-scale protein production for biotechnology and biopharmaceutical applications rely

ProteinQure 16 Aug 18, 2022
PatZilla is a modular patent information research platform and data integration toolkit with a modern user interface and access to multiple data sources.

PatZilla is a modular patent information research platform and data integration toolkit with a modern user interface and access to multiple data sources.

IP Tools 68 Dec 14, 2022
Sequence clustering and database creation using mmseqs, from local fasta files

Sequence clustering and database creation using mmseqs, from local fasta files

Ana Julia Velez Rueda 3 Oct 27, 2022
Python DSL for writing PDDL

PDDL in Python – Python DSL for writing a PDDL A minimal implementation of a DSL which allows people to write PDDL in python. Based on parsing python’

International Business Machines 21 Nov 22, 2022
dbt adapter for Firebolt

dbt-firebolt dbt adapter for Firebolt dbt-firebolt supports dbt 0.21 and newer Installation First, download the JDBC driver and place it wherever you'

23 Dec 14, 2022
The Official interpreter for the Pix programming language.

The official interpreter for the Pix programming language. Pix Pix is a programming language dedicated to readable syntax and usability Q) Is Pix the

Pix 6 Sep 25, 2022
Solves Maths24 problems for you!

maths24-solver Solves Maths24 problems for you! Enjoy this open scource project! You can edit modify and share! My wishes is for you to use this proje

6 Nov 07, 2021
Small projects for python beginners.

Python Mini Projects For Beginners I recently started doing the #100DaysOfCode Challenge in Python. I've used Python before, but I had switched to JS

Sreekesh Iyer 10 Dec 12, 2022
🔵Open many google dorks in a fasted way

Dorkinho 🔵 The author is not responsible for misuse of the tool, use it in good practices like Pentest and CTF OSINT challenges. Dorkinho is a script

SidHawks 2 May 02, 2022
A collection of tips for using MISP.

MISP Tip of the Week A collection of tips for using MISP. Published via BelgoMISP (todo) and this repository. Available in MD and JSON. Do you want to

Koen Van Impe 52 Jan 07, 2023