Questions tagged [meta-programming]
Meta-programming is the writing of computer programs with the ability to treat programs as their data. It means that a program could be designed to read, generate, analyze and/or transform other programs, and even modify itself while running.
137 questions
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Python 3.10+ deconstructing an over engineered solution to better understand how metaclasses work with properties, static methods, and classmethods
TL;DR
This question examines an over-engineered example of python metaclasses and dataclasses to create a LiteralEnum (for validating a stringly-typed keyword ...
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JVM bytecode instruction struct with serializer & parser
I am writing a java class file parsing & serialization library. As part of that i needed to implement a structure for the JVM bytecode instructions as well as come up with a way to parse & ...
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Decorator to validate that Python function arguments are positive
I have a list of functions whose parameters in the signature should be validated with the same criteria each time.
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Python colorized debug printer
In Python you can use print(locals()) to print a dictionary of all the local variables, but this has 3 shortcomings:
Double underscore variables will be included ...
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AutoBind TypeScript decorator
Idea is to have an AutoBind decorator which you could append in front of any method to have it preserve its own this, instead of manually binding it when called.
<...
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Change arbitrary arguments of function based on their names with a decorator
I ran across an issue that proved to be more complicated than I thought: Changing an arbitrary argument of a function purely based upon its name in Python - possibly via a decorator. I tried to ...
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Lightweight interface implementation in Python 3 using abstract classes
Here is my take at a lightweight interface implementation, where I focus on discoverability of suitable classes from strings (for simplicity, class name is used as an id). Each interface has it's own &...
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How can I make this CSV Importer code better of any code smell?
I wrote this method a few years ago in a Ruby on Rails project, which I think I am not proud of. How can I make this code better to show in-depth professionalism in Ruby?
lib/merchant/web_csv_importer....
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Ruby: Database Authentication Module
I have created a module that validates the credentials against different databases.
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Yet another reflection library
Tried to do my own implementation of reflection(introspection) for using in my next projects.
Is it optimized at compile time? If no, how can I improve it?
This macro is good interface for adapting ...
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LazyEnum with validation
Motivation
In the standard Python library enum, a subclass of Enum would create all its members upon class creation. This can ...
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A self contained parser generator implementation
This is a recreational project, I was trying to make a parser generator with a grammar inspired from: https://docs.python.org/3/reference/grammar.html
Unfortunately, understanding that specific ...
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config files for different development environments (Production, Dev, Testing)
I am following a guide that specifies how to manage different configurations (DB_URI, LOGGER_NAME, etc...) per development environments.
I create a config module ...
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Compile time logical operations for web framework in C++
I'm working on a web framework in C++ and there's this part that I need to do something like this:
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clean approach to decorator that takes optional keyword arguments [closed]
I write decorators a lot in my work. Sometimes you need to write "decorator that takes arguments", it usually turns out to be something like this:
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Inherit docstrings from specified parent
I was recently working on some python where I was working with multiple inheritance and mixins and stuff like that, and I wanted to inherit docstrings for specific functions, from specific parents (...
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Using metaclass to decorate derived classes to be `attrs` classes
I am currently developing a framework to facilitate writing controller programs for scientific instruments. I use attrs extensively in the internal parts of the ...
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Detecting existence of a class member
I wanted to detect if I have a member in a simple POD struct and after some searching and merging some methods I found on the web I've come up with this solution:
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Python class compressor
After watching this presentation, I decided that it would be a good project for me to undergo to practice my python skills. A summary of the presentation:
Jack ...
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Python decorator to support static properties
Classes in Python do not have native support for static properties. A meta-class can rather easily add this support as shown below. Are there any problems programmers might experience if they use this ...
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Python simple type checking decorator
I'd like to know your opinions on this minimal type-checking decorator (with @ annotations) to make type checking of a method while debugging like :
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Lazy evaluation function decorator
Suppose I have some expensive function expensive_computation which takes a long time to compute but it always returns the same value.
I want to avoid paying the ...
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Python breakpoints in Vim (Vimscript)
I recently decided that putting strategically placed print statements scattered about my python programs to debug was getting to be a little messy.
I had thought ...
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A simple decorator written as a class, which counts how many times a function has been called
Can I improve its typing? Is there any other improvement or pythonic change that you would do?
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Simple generic auto __repr__
Preface
At some point I was tired of writing & supporting __repr__ methods, so I've decided to write it once and reuse everywhere in my classes.
Since I'm ...
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Deserializing an XML Object without Reflection / Meta-Programming
I need to deserialize an XML file, without using any sort of "reflection" (or meta-programming). Instead, I need to do it via a raw object, that knows of it's structure and can properly identify and ...
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Metaclass to run a __first__ method for the first instantiation of a class
I had an idea for a __first__ special method for a class. It would be run after __new__ and before ...
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Cumulative profiler for a function
I have created a cumulative profiler,
meaning it runs a function several times in a row and prints the cumulative profiler results.
it's python >= 3.6 specific, but you can remove ...
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Decorator to add key parameter support to an existing sort function
Preface
sorted built-in function has key keyword-only parameter. Most of the custom implementations like the following for ...
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Using Python decorators to do Hoare Logic
I'm relatively new to Python from a strong Java background. I am trying to create a base class to do Hoare Logic. Function decorators seem to be the way to go with this. I've produced the following ...
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Function overloading in Python
Motivation
As an exercise, I wanted to try implementing function overloading in Python 3, i.e. to implement a way of defining multiple functions with the same name and then calling the appropriate ...
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550
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Using decorated methods in a subclass of deque to dump its state to a JSON file
I am sub-classing an object in python and I need to overload a bunch of the methods with very similar logic, essentially a call to super() and then some additional operations. I want to avoid ...
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Decorate instance method with (arbitrary) meta data in python
Requirements
What I need: attach meta information to methods, such that
it is 'easy' to retrieve all such methods for a given class instance
methods can still be called 'in a normal way', e.g. ...
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Encryption scripts using the module cryptography
Its meant to password protect python scripts by using encryption
It should use os.urandom(40)'s output in hex as the salt. The kdf (cryptography.io) is using Scrypt ...
user172978
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Generic framework to handle parameterized commands
I asked this question a while ago, and this was one of the comments:
There (mostly) seems to be a one-to-one mapping of a lot of your functions to IRC command verbs. For example, ...
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Class Decorator for Verifying Method-Level Permissions
After writing far too many if has_permission(user): statements at the head of my methods, I figured I would try my hand at writing a generic enough decorator to do ...
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Defining many HTTP request methods in a class using partialmethods
I am using an object that expects a keyword argument for every call, but I never intend to change it. In this case a timeout of 10. What is the best way to add a partialmethods for each attributes.
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Basic profiler - Python
I have created a simple profiler in Python, but I feel like there are better ways to do some things.
Terminology:
Section - a block of code to profile
Label - A name for a section to be used as a ...
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Writing a metaclass to ensure a class is thread-safe
Python allows the creation of classes to be modified via metaclasses. They can perform all sorts of operations that might appear to be magical to languages that do not have the capability. The goal of ...
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Marking a class as final or sealing a class
Which of these metaclasses should be preferred, and is there room for improvement?
Some people are not familiar with the philosophies that come with working in Python and have a desire embedded in ...
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Python Export Decorator
In Python, we use __all__ to explicitly denote the public API of a module or package. That looks like this:
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Scala code that loops through Java annotations decorating Scala classes
I have code written in Scala that reads annotations decorating other Scala classes. These annotations are written in Java. The sticking point is that annotations don't allow advanced data structures, ...
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Transforming stored procedures using Python regular expressions
I have to add some extra logic to about 80 similar stored procedures on my DWH server.
I thought that it would take pretty much the same time if I do it with Python and lots of googling (I have no ...
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Method arguments set object attributes
The code creates a meta class and its implementation to set the values passed in as arguments to methods on a class automatically on the object avoiding a lot of ...
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Decorator to return default argument values
I'm using Python 3.6. This code, used as a decorator to a python function, will cause the function to return a dict of POSITION_OR_KEYWORD arguments.
I used this ...
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Mutable Named Tuple - or - Slotted Data Structure
A question I answered on Stack Overflow asked for a mutable named tuple.
The naive answer would probably tell them they just want to define a custom object.
However, named tuples take up a lot ...
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Implement OO interfaces in Python
Edit: Whoops! I just remembered there's already an long-lived package for this, zope.interface. I'd like a review all the same.
This is a proof-of-concept ...
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Decorator to measure execution time of a function
This decorator adds the elapsed time to a function's attributes when applied.
My concerns:
Is the code pythonic?
Could this code be useful?
Should I just use the ...
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JavaScript Python Arrays
Here is an implementation in JavaScript that attempts to resemble Python-like arrays by mimicking slice comprehension for both getters and setters, as well as negative indexing from the end of the ...
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