Re: static object in a function: what if the constructor throws?

From:

Andy Champ <no.way@nospam.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Fri, 16 May 2008 17:48:22 CST

Message-ID:

<a6mdnfcjJ9--TrDVnZ2dnUVZ8uqdnZ2d@eclipse.net.uk>

Krzysztof Czainski wrote:

[code]
class Singleton
{
   Singleton(); // may throw
public:
   static Singleton& getInstance()
   {
     static Singleton instance;
     return instance;
   }
//...
};

int main()
{
   try {
     Singleton& s = Singleton::getInstance();
     //...
   }
   catch(...) { /* ... */ }
}
[/code]

Is it legal for the static variable constructor to throw? Would it
throw during the first call to getInstance, or earlier, or is it
unspecified when? Maybe someone has some other comments on this
implementation of the Singleton pattern?

A static variable within a function will be initialised the first time
the function is called (unlike a static global, or static class member
which is initialised before main() is called). That means the exception
will be thrown on the first call to getinstance.

Andy

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