Unsupported features in Python Tutor

Python Tutor currently does NOT support the following language features. Some of these features will eventually be supported, but others probably won't, due to implementation challenges and other priorities.

Email philip@pgbovine.net with more bug reports and use the "Generate shortened link" button to include a URL so that I can reproduce them.

For more details on project status and issue prioritization, check out these videos from March 2018:

• Python Tutor project status - 1 of 2 - common feature requests & feasible fixes
• Python Tutor project status - 2 of 2 - bigger feature requests & unlikely fixes

... and this earlier video from Oct 2017: Python Tutor Software Development Philosophy

C and C++

• unions
• some complex typedefs
• taking text input from the user using scanf(), cin >>, etc.
• code with memory-related errors: it will fail-fast using Valgrind Memcheck
• doesn't show when function parameters get mutated
• function return values are not visualized
• stack arrays without compile-time sizes
• read-only memory isn't visualized separately from the heap

JavaScript

• asynchronous event-driven code
  • including setTimeout, setInterval, etc.
  • promises, async/await
• anything that operates on webpages, such as DOM manipulation, alert(), prompt(), confirm(), etc.
• Date() object

Python

• some infinite loops: the server times out without showing partial results or good error messages
  • to cut down execution times, set Python breakpoints using #break comments
• asynchronous code
• random number generators and user input (via input() or raw_input()) sometimes don't work well together
• no 3rd-party library/module support: use the experimental "Python 3.6 with Anaconda" mode if you want to import many more modules from the Anaconda distribution
• (note: remember that Python 2 and 3 support slightly different kinds of language constructs)

Other unsupported features (language-agnostic)

• Stepping within a line of code to show how subexpressions get evaluated within that line
• Unicode doesn't work well in general (especially for Ruby and Python 2); use ASCII characters when possible
• Passing in command-line arguments via argv[] array
• Multi-threaded, concurrent, or asynchronous code
• Anything involving GUI programming or GUI/webpage components
• Reading data from external files; put all your data in strings when possible
• Interfacing with databases, network, filesystem, or other external resources
• Importing external 3rd-party libraries (try "Python 3.6 with Anaconda (experimental)" if you want to use more libraries)
• Code that is too large in size; shorten your code!
• Code that runs for too many steps (e.g., > 1,000 steps) or for a long time
  • shorten your code to isolate where you want to visualize and debug
  • or set Python breakpoints using #break comments
• If you're behind some kinds of firewalls or proxy servers, the visualizer may not work

Look through these issue trackers for additional bugs and unsupported features:

• https://github.com/pgbovine/OnlinePythonTutor/issues
• https://github.com/pgbovine/opt-cpp-backend/issues