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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
References must point to valid objects.
C and C++ could have non_nullable pointers, easily
Posted Sep 9, 2009 14:28 UTC (Wed) by foom (subscriber, #14868)
is perfectly valid. So they don't make a very good non-nullable pointer.
Posted Oct 18, 2009 22:52 UTC (Sun) by cmccabe (guest, #60281)
There shall be no references to references, no arrays of references, and no pointers to references. The declaration of a reference shall contain an initializer (8.5.3) except when the declaration contains an explicit extern specifier (7.1.1), is a class member (9.2) declaration within a class declaration, or is the declaration of a parameter or a return type (8.3.5); see 3.1. A reference shall be initialized to refer to a valid object or function. [Note: in particular, a null reference cannot exist in a well-defined program, because the only way to create such a reference would be to bind it to the object obtained by dereferencing a null pointer, which causes undefined behavior. As described in 9.6, a reference cannot be bound directly to a bitfield. ]
ISO/IEC 14882:1998(E), the ISO C++ standard, in section 8.3.2 [dcl.ref]
Posted Oct 19, 2009 3:47 UTC (Mon) by foom (subscriber, #14868)
I stand corrected.
I had always considered the "dereference" that occurs during the initialization of a reference
variable as syntax, rather than an actual memory operation, and thus the value of the pointer is
irrelevant at that point. Clearly the standard says otherwise.
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