Re: C++0x/1x exception specifications proposal: Compile-time checked

From:
Ioannis Vranos <ivranos@no.spamfreemail.nospam.gr>
Newsgroups:
comp.lang.c++
Date:
Tue, 22 Jan 2008 15:11:18 +0200
Message-ID:
<fn4q1q$15og$1@ulysses.noc.ntua.gr>
Ioannis Vranos wrote:

Compiler checks/errors:

Where the source code is available to the compiler, any
_nothrow(some_exception) specification at a function/member function,
must have at least one equivalent catch(some_exception) or catch(...)
exception handler at the function definition.

For example:

void somefunc() _throw()
{
  int *p= new int[10];

} _nothrow (std::bad_alloc)

should be flagged as a compiler error, because there is no
catch(std::bad_alloc) or catch(...) exception handler at the function
definition.

The following should be correct:

1 .

void somefunc() try _throw()
{
  int *p= new int[10]

} _nothrow (std::bad_alloc)

catch(std::bad_alloc)
{
 // ...
}

2.

void somefunc() try _throw()
{
  int *p= new int[10]

} _nothrow (std::bad_alloc)

catch(...)
{
  // ...
}

3.

void somefunc() try _throw()
{
  int *p= new int[10]

} _nothrow (...)

catch(...)
{
  // ...
}


Where the source code is available to the compiler, any
_throw(some_exception) specification at a function/member function, must
have at least one equivalent throw some_exception(); statement.

Remember each function/member function is a level, and its _throw
specifications are about exceptions they explicitly throw, and not about
"inherited" exceptions from other function/member function calls.

For example:

void somefunc() _throw(std::bad_alloc)
{

}

is a compiler error.

void somefunc() _throw(std::bad_alloc)
{
   throw std::bad_alloc();
}

is correct.

The following should be correct:

void somefunc() _throw()
{
  vector<int> vec(10);

  for (vector<int>::size_type i= 0; i< 10; ++i)
      vec.at(i)=5;
}

because it doesn't throw any exception by itself.

void somefunc() try _throw()
{
  vector<int> vec(10);

  for (vector<int>::size_type i= 0; i< 10; ++i)
      vec.at(i)=5;
} _nothrow (std::out_of_range)

catch(std::out_of_range)
{
   // ...
}

is correct and removes std::out_of_range from the exception
"accumulation" list.

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