Introducing Predictive Debugging: A Game-Changing Look into the Future
Introducing Predictive Debugging: A Game-Changing Look into the Future
With the introduction of debugging tools, software developers were empowered to interactively investigate the control flow of software programs to find bugs in live environments. At JetBrains, we've a
Kudos to the people who wrote this and it's great for people who use debuggers.
However I'd like to say that I haven't used one in years and don't see any reason to go back.
I've found that there's way simpler practices that have upped my development speed considerably. Simply think about what you're trying to do more carefully, and read over the code until you're sure it's good. It's the fastest way to iterate. Doesn't work? Read and think again.
You can put a format log in there. You can even comment it out, which can be useful later and for other people. It's plain and simple.
When I find myself using log all the time, it's either because I am tired, and I shouldn't be coding any way. Or impatient, which means I'm wasting time and should slow down. Or I have to deal with a library that has a shitty API, which you'll probably want to avoid using any way. And in that case you can use the interactive console to quickly try things out.
Honestly if there's anything I want to get better at it's test driven development. It tells you clearly whether it's working as expected or not.
I feel like you're missing out on a ton of awesome features by not using a debugger? Step backs are super useful, inline/live commands save you from re-running the code to see a different value, you can change values on the fly.
And it's nice to say "think about your code more" but when you're working with large teams, on legacy codebases, you don't often have the opportunity to "think about your code" because you're trying to decipher what someone wrote 3 years ago and they don't even work with the company anymore.
Have you ever tried my approach? It also works for understanding existing code bases. It just takes some practice, like working a mental muscle. So it might seem strange and ineffective at first.
If you do lots of trial and error and use the debugger you're basically externalizing the work, which slows it down and is less satisfying too imo.
Since adopting TDD, my debugger use has really dropped off. I think it's partially due to TDD encouraging me to develop more pure functions and push side effects to injectable (and thus mockable) objects.
But every so often I encounter a state that I can't understand how the code gets into, and in those cases being able to step through everything that's going on is incredibly helpful.
I may not use my debugger every day, but when I want it, I'm sure glad it's there.
When I have a real head scratcher like that I use log with a b c d. It's rare though and mostly due to me not paying attention or due to some convoluted calling graph.
Ya I've also switched to functional wherever possible. I still use objects for di.
Same here! Testing up front has made it extremely rare that I have to go back with a debugger later.
It's a little hard to iterate and think when you're adding to a complicated codebase you might not have worked with in several months, or even just a portion of a project that's seemed stable for a long time. In that scenario, debuggers are able to shorten the getting up to speed process by quite a bit.
My favorite tool in that case is jump to definition.
I am unsure just how revolutionary this feature is, though I am definitely interested in trying it and can see it's value. I've somewhat gotten away from Jetbrains, but I do still use and promote Rider for C# development so this is potentially a nice addition for my professional life.
am unsure just how revolutionary this feature is
It's not. This feature existed for dotnet in bugaid (which then got renamed to Ozcode) (which then got killed by Datadog) for the last 10 years already
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The code is already compiled. what do you mean it's preemptively compiled? If you're talking about executed, they explicitly called that out..
A prediction can also end at a function call the debugger is cautious about evaluating. That is for your own (or your software’s) well-being. Since code is executed during debugging, the debugger has to be sure that it’s not causing any mutations. When running the above example, we must confirm the evaluation of the int.TryParse method (more about that later):
As mentioned in the previous section, the predictive debugger won’t evaluate possibly impure functions to avoid side effects. As a human developer, you most certainly have more knowledge about the code, which is why we give you the possibility to forcefully evaluate a call by clicking the hint:
preemptively running source as it was written
It's not preemptively running source as it's being written, it's preemptively evaluating methods as you're debugging it
This looks like it's preemptive compiling, which isn't just unwise, it's potentially dangerous.
So I think what you might mean is preemptively evaluating methods at runtime? - which would be unwise / potentially dangerous - since it could cause side effect
For example, evaluating a method that increments something and modifies the state. So if it's preemptively called by the debugger, the state would be modified, and the actual invocation would be different
I installed the Resharper RC, and this is how it looks like in a small project that parses an excel file: https://i.imgur.com/g4s0P3h.png
So, in the example my debugger is still on the
allTheFieldsEmptyline and hasn't ran it yet, but resharper already evaluated it to false. Then it also greyed out everything in theif(allTheFieldsEmpty)block, since it knows it wouldn't hit thatThe next line you can see there was a warning, "Possible impure evaluation" - which is that I assume you were talking about, and it didn't evaluate that yet. I can click the box and make it evaluation it.
The debugger inspects the method, as the article mentions, it check for the PureAttribute - indicating that it's safe to use
After I marked that
GetMappingFieldmethod as Pure, it actually did evaluate it without any interaction, and it predicted it would throw an exception https://i.imgur.com/zQ0K3Ge.png - seems pretty useful so far
