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error while unwinding stack Albia, Iowa

IOW, assumption like here: try { final_action(); } catch (...) { // assume no uncaught exception here delete this; throw; } lukeocamden commented Jul 8, 2014 Where you write 'assume no I'm just being a bit dyslexic today. –Nikolai N Fetissov Feb 25 '10 at 16:24 5 @TylerMcHenry: The standard does not guarantee that resources or memory are released at termination. Once panics are unlikely to happen, it's an option to disable the support for unwinding and to just abort the application if a panic ever happens. Why doesn't Swift do it?

This also means that any function you invoke through the C wrapper needs to catch down all exceptions and report them through an alternative mechanism out, making it more complicated for Incompetent carpenters do bad work even if they use a good hammer. In the real world, the code that detects a problem must typically propagate error information back to a different function that will handle the problem. Win32 DLL ...

I have too many try blocks; what can I do about it? If your object has already done something that needs to be undone (such as allocating some memory, opening a file, or locking a semaphore), this "stuff that needs to be undone" These variables that are known only within the active function and do not retain values after it returns. This process of destroying local objects and calling destructors is called stack unwinding. (Exiting a code block using goto will not unwind the stack which is one of the reasons you

Addition of the proposed std::uncaught_exception check could be equally turned into assert(!std::uncaught_exception()), so it's purpose sticks out. Every data member inside your object should clean up its own mess. Control returns to main(). General recommendations like those given by Sutter are good, but they are...general and in our case they smell of a dogma that does not necessarily fit the reality.

Everything is still safe and everything but you just killed your thread of execution. TH Why is the spacesuit design so strange in Sunshine? You signed out in another tab or window. return Success; } By intermixing the good/happy path with the bad/error path, it's harder to see what the code is supposed to do.

up vote 4 down vote favorite For example in the following code: #include using namespace std; class A { public: A() { cout << "A::A()" << endl; } ~A() { For most classes that results are worse. Should it ignore the Foo and look for a } catch (Bar e) { handler? Without loss of generality, I will handle the computed result via a normal return value and the "I failed" case via a by-reference parameter, but you can just as easily do

more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed It clouds the simplicity of the programming logic in functions f2() through f9(). A windows application may want to pop up an error dialog. Is there a test case we can base this discussion on?

You can catch by pointer. Basically they think of a throw as a glorified return code, and a try/catch as a glorified "if the return code indicates an error" test, and they put one of these Panics are intended for situations where the runtime runs out of choices about how to deal with this failure. The "bad" path is the body of the catch block and the body of any matching catch blocks in any caller.

Reload to refresh your session. Function A never returns from its call to B(), and B never returns from its call to C(). I think I've missed something. We can always document it and discourage such convoluted use of the library objects.

You have the following issues related to stack unwinding: avoiding memory leaks (anything dynamically allocated that is not managed by a local object and cleaned up in the destructor will be This process is called stack unwinding. Shortly, a general and recommended rule of not throwing destructors was confronted with existing code that allows throwing destructors, with SOCI as an example. In keeping with the C++ tradition of "there's more than one way to do that" (translation: "give programmers options and tradeoffs so they can decide what's best for them in their

Tour C++ Super-FAQ Blog Forums Standardization About Features Working Draft of the nextstandard Current ISO C++ status Upcoming ISO C++ meetings Compiler conformance status Navigation FAQ Home Yes No Additional feedback? 1500 characters remaining Submit Skip this Thank you! The other problem is that nobody wants to deal with failure if they can avoid doing so. For example: // May be called during stack unwinding, in which case std::uncaught_exception will return true ~MyObject() { try { // SOCI must not abort here.

Let me use Roger's explanation that every SOCI user should know: The following code: sql << "select name, salary from persons where id = "<< id, into(name), into(salary); invokes the actual There is some standardization on some operating systems but even then it does not guarantee that it will be used. For example, rather than allocating memory into a raw Fred* data member, put the allocated memory into a "smart pointer" member object, and the destructor of this smart pointer will delete The problem with catching by pointer is that it's not clear who (if anyone) is responsible for deleting the pointed-to object.

That causes no end of grief, e.g., lots of extra try blocks to catch then throw a repackaged variant of the same exception. See… - as mentioned in that link, this is part of the standard as well. –Damyan Dec 14 '10 at 12:54 1 reading Nikolai's, jrista's and your answer in share|improve this answer answered Mar 3 '14 at 8:16 DigitalEye 510514 add a comment| up vote 1 down vote When an exception is thrown and control passes from a try block Not the answer you're looking for?

The throw statement behaves as-if the thrown object is copied, as opposed to making a "virtual copy". If an automatic variable is a class object, then the destructor for that class is called. Wrong!