CODEWITHSUNDEEP
c++exceptiontry-catchc++buildercatch-block
Александр Кулагин
Александр Кулагин

Reputation: 75

How to get the current exception object in C++ Builder (replacement for ExceptObject)?

I am looking for a function/code that returns the current exception object. In other words, the exception object that represents the exception currently being handled (by the catch block).

For example:

  try
  {
    // throws an exception
  }
  catch (const std::exception& Exc)
  {
    DoSomething();
  }

void DoSomething() {
  // How to get the "Exc" here?
}

In other words, I need a C++ equivalent of Delphi's ExceptObject function.

The code above is just an example. The real code looks more like this:

  catch (...)
  {
    A3rdPartyCode();
  }

void A3rdPartyCode() {
  MyCode();
}

void MyCode() {
  // Does not work, returns NULL:
  TObject* = ExceptObject(); 

  // ???
  // Need to know the current exception, if present
}

Upvotes: 2

Views: 117

Answers (1)

zdf
zdf

Reputation: 4808

Most likely you are looking for a solution in the wrong way, trying to match Delphi and C++ line for line. Anyway, here's an example of how std::current_exception can be used:

#include <iostream>
#include <exception>

void f()
{
  throw "exception from f()";
}

std::exception_ptr pce;

void g() noexcept
{
  try
  {
    f();
  }
  catch (...)
  {
    pce = std::current_exception();
  }
}

void h() noexcept
{
  try
  {
    if ( pce )
      std::rethrow_exception(pce);
  }
  catch (const char* e)
  {
    std::cout << e;
  }
}

int main()
{
  g();
  h();
}

std::current_exception is useful, for example, if you are processing a collection in a secondary thread using a function that can throw for each item in the collection. Instead of interrupting the processing, you can store the exception and forward it to the main thread later.

Upvotes: 3

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