Live Debugging in Smalltalk
Why Hacker News recommends it
HN cites it as a concise demo of live debugging and editing code in a running Smalltalk environment.
What it is
A brief demo of the Smalltalk debugger, including defining a method that doesn't exist yet while the program is stopped mid-crash.
Recommended by 0 HN commenters across 0 different months, 2012 to 2017.
What Hacker News said
Cites tree_of_item · 2012-05 · on “The Essence of Dynamic Typing”
A small example of refactoring running code is at [this video] And a more lengthy example of writing tests first, letting the code fail, and fixing things in the debugger: [LINK] This is kind of like writing code that doesn't exist or doesn't work, and letting the type checker guide you through the things you need to fill in. The difference is that Smalltalk is actually executing your code, so you can see actual values rather than just type errors, and it will keep trying to execute your code while you change things. It might be possible to do something like that with static typing, but I think the real issue is that most advocates of static typing wouldn't really _want_ to mess around with progr
Cites jerf · 2017-10 · on “Saying Goodbye to Firebug”
This may have been posted in 2008, but the tech it is demoing was decades (yes, plural) old by then: [this video] This video is a simple demonstration of very mature tech, not a demo of something hot and new. That's a demo of a Smalltalk environment with the programmer deliberately writing some code that crashes, going into the debugger, adding the method on the fly, and then having the original method call complete despite the method not yet having existed. It isn't quite true that there is nothing new under the tech sun... but there's certainly less new than most people seem to think.
Cites robertkrahn01 · 2017-12 · on “Smalltalk’s Productivity”
Smalltalk has a meta API that is designed to allow introspection and modification of both static and dynamic code entities [1,2]. Static entities such as classes and methods (and depending on your Smalltalk implementation namespaces and object versions) can be modified at runtime, i.e. while your program is running you can make a change and get an immediate effect. This is now known as "live" programming, however, it is notably different from your typical "hot reload" implementation in that it knows how to apply changes for individual code entities. E.g. if you modify a method you don't need to reload the entire class or module or entire runtime. For me, this feature alone makes for a big pr