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.

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38 views

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 ...
6
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2answers
265 views

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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0answers
26 views

Simplified Bash getopts flow

I've always found the boilerplate needed to use getopts correctly fairly fiddly and verbose, and was motivated to try to abstract it away. I wanted to try ...
4
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1answer
51 views

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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1answer
34 views

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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0answers
74 views

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: ...
3
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1answer
46 views

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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0answers
29 views

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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0answers
46 views

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 ...
8
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1answer
334 views

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: ...
7
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2answers
94 views

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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1answer
638 views

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 ...
3
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1answer
115 views

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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1answer
100 views

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 ...
4
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0answers
115 views

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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1answer
77 views

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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3answers
129 views

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 ...
4
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1answer
68 views

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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0answers
42 views

Python script to add unittest decorators to source code files

This is a simple Python script to add @unittest.skipUnless() decorators in a specified format above every function starting with ...
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0answers
63 views

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 ...
3
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0answers
76 views

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 ...
4
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1answer
55 views

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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0answers
119 views

@bound decorator for TypeScript

I'm working on an angular codebase that very frequently uses constructs like: <c-whatever [action]='doSomething.bind(this)'> to pass reference to the ...
6
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1answer
147 views

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 ...
3
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1answer
377 views

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 ...
12
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1answer
224 views

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 ...
3
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1answer
151 views

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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2answers
408 views

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 ...
3
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1answer
58 views

Two java classes with different annotation values only [closed]

Consider two classes: First ...
12
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1answer
167 views

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, ...
6
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2answers
189 views

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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1answer
89 views

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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1answer
69 views

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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0answers
270 views

Sealing class attributes in Python

Over two years ago, someone asked a question on Stackoverflow about how to seal classes and attributes in Python after coming from a background in C#. The best answer to the question is that Pythonic ...
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0answers
538 views

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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0answers
1k views

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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2answers
1k views

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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0answers
70 views

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, ...
3
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1answer
391 views

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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1answer
236 views

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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0answers
75 views

Dependency resolving functions

Written in Python 3.6 and I must admit, this might be too far... Tell me what you think of this code. There must be a better way... It's (another decorator...) that allows you to compose functions ...
7
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1answer
620 views

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 ...
10
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2answers
3k views

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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0answers
650 views

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 ...
14
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1answer
19k views

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 ...
2
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1answer
98 views

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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0answers
91 views

Optionally disabling a call-tracing decorator in Typescript

I have a Typescript decorator that traces method calls. The decorator can be applied at both the class level and method level. I want to disable the decorator in production. Is this code the most ...
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2answers
88 views

A shim to make make Node GRPC bindings more JavaScript-y

This function allows me to write this code ...
11
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3answers
142 views

Mass and length calculator using Perl 6 custom operator

I am studying chemistry in the university, and then I try to write all the things in the textbook with Perl6 or Perl, like balancing the chemical formula or other process! Then I encountered the ...
12
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1answer
376 views

Field Can Be Made Readonly

Here is my Field Can Be Made Readonly analyzer and quick fix. I would appreciate tips on how to improve my code, and on missed test cases. First, the rules it works with: It will only fire on ...