Uniform initialization in C++0x, when to use () instead of {}?

Question

Is there a rule of thumb to decide when to use the old syntax () instead of the new syntax {}?

To initialize

Answer 1

Take a look at this:

http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=453&rll=1

The use of a {}-style initializers on a variable has no direct mapping to the initialization lists on any constructors of the class. Those constructor initialization lists can be added/removed/modified without breaking existing callers.

Basically the different behavior of the container is special, and requires special code in that container, specifically a constructor taking a std::initializer_list. For POD and simple objects, you can use {} and () interchangeably.