What is pyqt?

PyQt is a set of Python bindings that let you use the Qt application framework (a powerful C++ library for building graphical user interfaces) directly from Python. In simple terms, it lets you write desktop apps with windows, buttons, menus, and more using Python code.

Let's break it down

  • Qt: A cross‑platform GUI toolkit written in C++. It handles drawing windows, handling mouse clicks, etc.
  • Python bindings: A “bridge” that translates Python commands into Qt’s C++ calls.
  • PyQt: The actual package you install (pip install pyqt5 or pyqt6). It provides Python classes like QMainWindow, QPushButton, and QLabel that map to Qt’s C++ classes.
  • Signal & Slot: A communication system in Qt. In PyQt you connect a signal (e.g., a button click) to a slot (a Python function) to make things happen.

Why does it matter?

  • Fast development: Write GUI code in Python, which is easier and quicker than C++.
  • Cross‑platform: One codebase runs on Windows, macOS, and Linux without changes.
  • Rich features: Access to Qt’s advanced widgets, graphics, multimedia, and networking tools.
  • Large community: Plenty of tutorials, examples, and third‑party widgets.

Where is it used?

  • Desktop utilities (file managers, text editors, image viewers).
  • Scientific tools (data visualisation apps, lab equipment interfaces).
  • Business software (inventory systems, point‑of‑sale terminals).
  • Prototyping: developers quickly mock up UI concepts before moving to other languages.

Good things about it

  • Mature and stable; Qt has been around for decades.
  • Very comprehensive: over 600 classes covering UI, graphics, networking, etc.
  • Supports modern UI designs with stylesheets (similar to CSS).
  • Good documentation from both Qt and the PyQt project.
  • Can be combined with other Python libraries (NumPy, pandas, Matplotlib) for powerful apps.

Not-so-good things

  • Licensing: PyQt is GPL/commercial; if you need a closed‑source app you must buy a commercial license or use the alternative LGPL‑licensed PySide.
  • Larger executable size: Bundling a PyQt app often results in bigger files compared to pure Python tools.
  • Learning curve: Understanding Qt’s signal/slot system and its extensive class hierarchy can be overwhelming for absolute beginners.
  • Performance: For very heavy graphics or real‑time tasks, native C++ Qt may be faster than Python‑based PyQt.