This Python exception handling library shows a great stacktrace, I hope it can give some inspiration to @madExcept and others. I especially like the function parameter values are shown in the stack trace, but not sure it's possible with Delphi.

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This Python exception handling library shows a great stacktrace, I hope it can give some inspiration to @madExcept and others. I especially like the function parameter values are shown in the stack trace, but not sure it's possible with Delphi.
https://github.com/Qix-/better-exceptions

Comments

  1. A. BouchezMarch 22, 2017 at 11:19 PM

    You just can't get the function parameters nor the source code line with a compiled executable!

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  2. Thomas Mueller (dummzeuch)March 22, 2017 at 11:58 PM

    A. Bouchez jcldebug can get the source line using the map file. It's beyond me why that functionality isn't available in Delphi out of the box.

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  3. Jacek LaskowskiMarch 23, 2017 at 12:06 AM

    plus.google.com - Why Delphi (like other developer environments) natively not included full cal...

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  4. Lars FosdalMarch 23, 2017 at 12:21 AM

    I love EurekaLog (and I hate it when it's not available for a new Delphi version).

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  5. Eric GrangeMarch 23, 2017 at 12:44 AM

    Delphi (and all optimized binaries) ofttimes mutates the parameters as part of optimizations, so you cannot get the value at entry point without "saving" the parameters somewhere.

    I suppose you could get "close" in Delphi by compiling with optimizations off, stack frames off, and running your binary inside a debugger. Not sure it would be worth the trouble though, might as well go for a script language directly, you'll gain plenty of other debugging niceties.

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  6. Lars FosdalMarch 23, 2017 at 12:54 AM

    Eric Grange We've turned to stuffing context info into a TArray buffer which is added to any exception logging. That will at least give us a bit more to work from when trying to reproduce a problem.

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  7. Jeroen Wiert PluimersMarch 23, 2017 at 12:59 AM

    The debugger tries to get the parameter values in the stack, but is often wrong because of what Eric Grange mentions.

    I like the idea by Lars Fosdal on storing context as you can tailor that to your needs. Be sure not to cause exceptions filling that context though (:

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  8. Lars FosdalMarch 23, 2017 at 1:05 AM

    Jeroen Wiert Pluimers It is fairly brute force. A threadvar and simple methods to add to, clear and retrieve the buffer. Simple, but it works. Well, there was that one time where we forgot to clear in a loop... Let's just say there were copious amounts of context for that first error.

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  9. Edwin YipMarch 23, 2017 at 1:06 AM

    Jeroen Wiert Pluimers I remember I saw a c# library which can inject any code into any methods at the beginning or at the end. I don't remember its name nor I know if it's possible with Delphi, or it's completely another thing not relating to stack tracing here? Forgive me didn't dug into this field deep enough :P

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  10. Lars FosdalMarch 23, 2017 at 1:20 AM

    Edwin Yip - Injection is possible in .NET intermediate code, but way harder in a compiled language such as as Delphi. You could in theory use a preprocessor to inject code into the source code before compilation - but then you would run into issues when debugging.

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  11. Edwin YipMarch 23, 2017 at 1:33 AM

    Lars Fosdal I think so, I guess it depends on the reflection feature of the .net framework.

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  12. Jeroen Wiert PluimersMarch 23, 2017 at 2:18 AM

    Edwin Yip there are even tools on the .NET platform that do full IL rewriting to do this. You need a great detours library on Windows to get that done well for native code.

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  13. A. BouchezMarch 23, 2017 at 2:59 AM

    Thomas Mueller This was not my point. I know that you can get the source code line number (I've implemented it in SynLog, in a more efficient way than jcldebug), but not the source code itself!
    This functionality is out-of-the box in FPC, BTW.

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  14. Lars FosdalMarch 24, 2017 at 12:18 AM

    A. Bouchez Can it unwind the stack to give you the full context of execution?

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  15. A. BouchezMarch 24, 2017 at 2:29 AM

    Lars Fosdal Do you mean in FPC? Yes, you have the stack trace, on all supported platforms. :)
    See e.g. http://wiki.freepascal.org/Logging_exceptions

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  16. A. BouchezMarch 24, 2017 at 2:30 AM

    Lars Fosdal Do you mean with FPC? Yes, on all supported platforms - see wiki.freepascal.org - Logging exceptions - Free Pascal wiki

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  17. Lars FosdalMarch 24, 2017 at 2:52 AM

    A. Bouchez I was thinking of the SynLog code.

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  18. A. BouchezMarch 24, 2017 at 10:12 AM

    Lars Fosdal Yes, of course, even with Delphi 5 or under Kylix. See https://synopse.info/files/html/Synopse%20mORMot%20Framework%20SAD%201.18.html#TITL_16
    Including source code line numbers. And in fact, the .map content is embedded and compressed in a very efficient way - better than alternatives I know.

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  19. Tommi PramiMarch 26, 2017 at 1:38 PM

    /sub

    ReplyDelete

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