hot code swapping

[andrewrk]

• Have the compiler run continuously, watching the file system for source
  changes and automatically perform multithreaded compilation to build projects
  quickly.
• Hot code swapping. When integrated with the previous feature, you could
  press "save" in your editor and see the change immediately in your running
  software.

Of course this only works for some kinds of changes - obviously if you make changes to your initialization code, you won't see a difference. But it would probably work at the function level, so you could swap out any individual function for a new one.

[PavelVozenilek]

This feature (automatic rebuild in background & hot code swapping) is available for C++ in Projucer IDE, built upon LLVM infrastructure.

Old demo 1, old demo 2, few implementation details.

Be aware that it took several years to implement and the implementor said that "it was the most complicated thing I ever did".

[0joshuaolson1]

@PavelVozenilek The Projucer link has died, sadly.

[PavelVozenilek]

Information from the dead link is probably here:
https://forum.juce.com/t/demo-screencast-of-the-projucer/9218
and here:
http://web.archive.org/web/20130808104856/http://rawmaterialsoftware.com/viewtopic.php?f=2&t=9794

[ccll]

I always wonder how should hot-swap deal with data (data structure layout and long-lived in-memory state), it seems rather difficult compared to hot-swap stateless code (like a pure function).
In some languages which support closure, it's even more complicated.
Are there any articles on this subject?

[isaachier]

@ccll that is the biggest issue. Doing it in C/C++ is currently possible using a dynamically loaded library. See this blog post on the topic.

[themagnet]

here https://molecular-matters.com/products_livepp.html is a commercial product which realizes hot-reload for c/c++ projects