How to catch the exception in initialization list?

问题:

This question already has an answer here:

• Catching exceptions from a constructor's initializer list 5 answers

I have a question about how to catch the exception in the initialization list.

For example, we have a class Foo derived from Bar

class Foo {

public:
Foo(int i) {throw 0; }

}

class Bar : public Foo{

public:

Bar() : Foo(1) {}

}

回答1:

I think the syntax is like this (even though it's better to catch such things in the caller. And what are you going to do once you caught it?)

Bar::Bar()
try
  : Foo(1)
{
}
catch( const SomeException &e )
{
}

回答2:

C++ has a mechanism for doing so, but it is rarely used. It is the function try block:

Bar::Bar()
try
  : Foo(1)
{
}
catch( Something )
{
}

See this classic gotw, which outlines why it should only be used to translate exceptions (e.g., exception type FooException becomes BarException).

回答3:

I believe this should be caught by the procedure creating the object.

回答4:

Consider replacing the troublesome instance with a boost::optional. Then you can defer its initialization into the body of the constructor.