vxworks programmer's guide.pdf - DAQ Plone Site

5
C++ Development
consult any standard C++ reference (a good one is Stroustrup, The C++
Programming Language, Third Edition). For documentation on the GNU
implementation of the Iostream library see
5.3.1 Language Features
We support many but not all of the new language features contained in the recently
approved ANSI C++ Standard. Tornado 2.0 has support for exception handling
and run-time type information, as well as improved template support. We do not
yet support the namespace feature although the compiler will accept (and ignore)
references to the std namespace.
5
Exception Handling
Our C++ compiler supports multithread safe exception handling by default. To
turn off exception handling support use the -fno-exceptions compiler flag.
Using Exceptions
You may have code which was designed around the pre-exception model of C++
compilation. Your calls to new may check the returned pointer for a failure value
of zero, for example. If you are worried that the exception handling enhancements
in this release will not compile your code correctly, you could adhere to the
following simple rules:
■
■
Use new (nothrow).
Do not explicitly turn on exceptions in your Iostream objects.
■
Do not use string objects or wrap them in “try { } catch (...) { }” blocks.
These rules derive from the following observations:
■
The GNU Iostream does not throw unless IO_THROW is defined when the
library is built and exceptions are explicitly enabled for the particular Iostream
object in use. The default is no exceptions. Exceptions have to be explicitly
turned on for each iostate flag that wants to throw.
■
The STL does not throw except in some methods in the basic_string class (of
which string is a specialization).
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