C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Forbid C-style Casts with References          C++Talk.NET Forum Index -> C++ language, library and standards View previous topic :: View next topic   Author Message Tomás Guest Posted: Thu May 11, 2006 4:21 pm    Post subject: Forbid C-style Casts with References First of all, there's no references in C. While C-style casts are deprecated in C++, they may still be used. However, why was their functionality *extended* to allow casting to a reference? Here's some sample code which compiles, but which I rather wish would not compile: void ModifyConstantObject( const int& a ) { ++(int&)a; /* This should have to be: ++const_cast<int&>(a); */ } int main() { int const a = 7; ModifyConstantObject(a); } I propose that C-style Cast with references should be banned (i.e. they should not compile). -Tomás --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Jonathan Biggar Guest Posted: Thu May 11, 2006 10:21 pm    Post subject: Re: Forbid C-style Casts with References Tomás wrote: Quote: First of all, there's no references in C. While C-style casts are deprecated in C++, they may still be used. However, why was their functionality *extended* to allow casting to a reference? Because references were added to the language before the new-style casts were, and so the extension was necessary. At that point, code was written to use C-style casts on references, so making it illegal breaks working code. -- Jon Biggar Floorboard Software jon (AT) floorboard (DOT) com jon (AT) biggar (DOT) org --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Gene Bushuyev Guest Posted: Fri May 12, 2006 6:21 pm    Post subject: Re: Forbid C-style Casts with References "Tomás" <NULL (AT) NULL (DOT) NULL> wrote in message news:sTH8g.9041$j7.305354 (AT) news (DOT) indigo.ie... [...] Quote: I propose that C-style Cast with references should be banned (i.e. they should not compile). Treating references differently from the other types would have adverse effect on templates. Since C style cast is not equivalent in general case to any of c++ casts, it makes sense to keep it for all types instead of writing specialization for references every time it is used. E.g., template<class To, class From> To c_cast(From from) { return (To)from; } int main() { int i = 0; long& l = c_cast<long&>(i); } -- Gene Bushuyev (www.gbresearch.com) ---------------------------------------------------------------- There is no greatness where there is no simplicity, goodness and truth. ~ Leo Tolstoy --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top David R Tribble Guest Posted: Sat May 13, 2006 4:21 pm    Post subject: Re: Forbid C-style Casts with References Tomás wrote: Quote: First of all, there's no references in C. While C-style casts are deprecated in C++, they may still be used. However, why was their functionality *extended* to allow casting to a reference? Jonathan Biggar wrote: Quote: Because references were added to the language before the new-style casts were, and so the extension was necessary. At that point, code was written to use C-style casts on references, so making it illegal breaks working code. You compiler vendor is free to issue a warning in these cases, though. --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Ron Natalie Guest Posted: Sun May 14, 2006 4:21 am    Post subject: Re: Forbid C-style Casts with References Tomás wrote: Quote: First of all, there's no references in C. While C-style casts are deprecated in C++, they may still be used. They aren't officially called C-style casts. They don't behave like casts do in C really. They aren't deprecated either. There is even one operating mode of the C-style cast for which there is no C++ equivelent. Quote: However, why was their functionality *extended* to allow casting to a reference? Because it was needed, the other casts case later. Quote: --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. 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