🪴 Peter Garden

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20250405-python-uv

4 min read

python-uv

(166) uv: An Extremely Fast Python Package Manager - YouTube

✅ What is uv venv?

uv venv is a faster alternative to python -m venv or virtualenv, built into the uv tool. It creates a virtual environment and installs dependencies blazingly fast.

🔧 Prerequisite

Make sure uv is installed:

curl -Ls https://astral.sh/uv/install.sh | sh

🧪 How to use uv venv

1. Create a new virtual environment

uv venv .venv

This creates a .venv folder in the current directory.

2. Activate the environment

On macOS/Linux:
source .venv/bin/activate
On Windows (PowerShell):
.venv\Scripts\Activate.ps1

📦 Install packages

Once activated, use uv pip just like pip:

uv pip install fastapi uvicorn

Check installed packages:

uv pip list

💾 Save dependencies

To generate requirements.txt:

uv pip freeze > requirements.txt

📁 Typical Workflow

# Create and enter project
mkdir my-fastapi-app && cd my-fastapi-app
 
# Create a virtual env
uv venv .venv
 
# Activate it
source .venv/bin/activate
 
# Install packages
uv pip install fastapi uvicorn
 
# Save deps
uv pip freeze > requirements.txt

Let me know if you want a clean project template using uv, FastAPI, and PostgreSQL — I can generate one for you to get started fast 🔥

I just :

uv pip (pypy support version): uv add ipdb dubugger(better) uv init/ source it

Great question — uv currently does not support installing alternative Python interpreters like PyPy (as of early 2025). It’s mainly focused on being a drop-in faster replacement for pip, pip-tools, and virtualenv, but not a Python version manager like pyenv.

✅ So, what’s possible with uv?

  • ✔️ Fast pip-style installs (uv pip install fastapi)
  • ✔️ Blazing-fast venv creation (uv venv .venv)
  • ✔️ Works with your existing Python interpreter (system or virtualenv)
  • ❌ Does NOT install other Python versions or interpreters (like PyPy, CPython 3.12, etc.)

🚀 If you want to use PyPy with uv

You can manually install PyPy, then run uv from that interpreter:

Step-by-step:

  1. Download PyPy:
    https://www.pypy.org/download.html

  2. Extract and set it up:

    tar -xf pypy3.10-v7.3.12-linux64.tar.bz2
cd pypy3.10-v7.3.12-linux64

  3. Use PyPy as your Python interpreter with uv:

    ./bin/pypy3 -m uv venv ../pypy-env
source ../pypy-env/bin/activate
uv pip install fastapi

✅ uv will work as long as you’re in a virtual environment created with a PyPy interpreter.

🔁 Summary

ToolPython Version ManagementPackage/Env SpeedPyPy Support
pyenv✅ Yes❌ Slower✅ Yes
uv❌ No✅ Super Fast⚠️ Manual
asdf✅ Yes (via plugin)⚠️ Okay✅ Yes

Let me know if you want a ready-to-run PyPy + uv environment template or script — I can set that up for your system!

Effective Use of Python ‘logging’ Module - Yuxin’s Blog

#!/usr/bin/env python
import sys
import subprocess
import time
import os
import argparse
 
 
def write(b: bytes):
    os.write(1, b)
 
 
def has_tmux():
    return "TMUX" in os.environ
 
 
def tmux_passthrough(b: bytes):
    return b'\x1bPtmux;' + b.replace(b'\x1b', b'\x1b\x1b') + b'\x1b\\'
 
 
def tmux_passthrough_pipe(buf: bytes):
    curr = 0
    while True:
        start = buf.find(b'\x1b', curr)
        if start < 0:
            break
        end = buf.find(b'\x1b\\', start + 1)
        if end < 0:
            break
        write(buf[curr:start])
        write(tmux_passthrough(buf[start:end + 2]))
        curr = end + 2
 
 
def clear_kitty():
    sys.stdout.buffer.write(b'\033Ptmux;\033' + b'\033_Ga=d,d=A\033\033\\' + b'\033\\')
 
 
if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    cmds = parser.add_subparsers(title="subcommands", dest="command")
    p = cmds.add_parser("kittyimg",
                        help="Show an image using kitty protocol. Works OKish in tmux.")
    p.add_argument("input", help="image file")
    p.add_argument("--ttl", type=int, default=3, help="time to clear the image, if in tmux")
    p = cmds.add_parser("passthrough", help="tmux-passthrough for stdin. for debugging.")
    p = cmds.add_parser("clearimg", help="clear kitty image")
    p = cmds.add_parser("notify", help="send desktop notifications (OSC99)")
    p.add_argument("message", help="notification message")
 
    args = parser.parse_args()
 
    if args.command == "passthrough":
        buf = sys.stdin.buffer.read()
        tmux_passthrough_pipe(buf)
    elif args.command == "kittyimg":
        fname = args.input
        if not has_tmux():
            cmd = f'timg -C -pk "{fname}"'
            os.system(cmd)
        else:
            cmd = f'timg -C -g x100 -pk "{fname}"'
            buf = subprocess.check_output(cmd, shell=True)
            write(tmux_passthrough(buf))
            if args.ttl > 0:
                time.sleep(args.ttl)
                clear_kitty()
    elif args.command == "clearimg":
        clear_kitty()
    elif args.command == "notify":
        payload = b'\x1b]99;;' + args.message.encode('utf-8') + b'\x1b\\'
        if has_tmux():
            payload = tmux_passthrough(payload)
        write(payload)
        write(b'\a')  # bell
  • tmux escape config for pass through , ssh with kitty image

copier

Example Code

More examples are forthcoming, but for now please see absl-py’s own tests for examples of how to use absltest.

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