C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Strongly type doubles?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Joseph Turian Guest Posted: Sun Nov 26, 2006 10:11 am    Post subject: Strongly type doubles? I want to create several types of double, e.g. D1 and D2. I want strong typing, such that a function defined for D1 will not accept a D2 argument. One solution is: struct D1 { double d; }; However, the usage is cumbersome (I have to access member variable d), I don't have any operators defined, and object creation is more expensive than for native types (right?). Can someone propose an alternate solution that enforces the type safety I require? Thanks, Joseph Back to top kwikius Guest Posted: Sun Nov 26, 2006 10:11 am    Post subject: Re: Strongly type doubles? Joseph Turian wrote: Quote: I want to create several types of double, e.g. D1 and D2. I want strong typing, such that a function defined for D1 will not accept a D2 argument. One solution is: struct D1 { double d; }; However, the usage is cumbersome (I have to access member variable d), I don't have any operators defined, and object creation is more expensive than for native types (right?). Can someone propose an alternate solution that enforces the type safety I require? It is perfectly possible to make your own types that act like doubles, but with whatever semantics you want to design in. Its not trivial though to get all the details the way you want them to be. The link here is to my code for a physical quantity type, but the underlying principle involved is the same for a strongly typed double: http://quan.sourceforge.net/index.html. For variables the assembly code is indistinguishable from that using doubles in most cases (using VC8.0 with a very good optimiser), however the code for literal constants is better optimised for inbuilt types so you do seem to lose performance there. regards Andy Little Back to top Markus Svilans Guest Posted: Sun Nov 26, 2006 10:11 am    Post subject: Re: Strongly type doubles? Joseph Turian wrote: Quote: I want to create several types of double, e.g. D1 and D2. I want strong typing, such that a function defined for D1 will not accept a D2 argument. One solution is: struct D1 { double d; }; However, the usage is cumbersome (I have to access member variable d), I don't have any operators defined, and object creation is more expensive than for native types (right?). Can someone propose an alternate solution that enforces the type safety I require? Thanks, Joseph If you use the structs, you could define conversion operators for D1 and D2: struct D1 { double d; operator double () { return d; } }; Then you will be able to use them in mathematical expressions because the conversion to double will take place automatically: D1 a, b; a.d = 15; b.d = 25; double c = a * b; You will also be able to have functions that accept D1 objects, but not raw doubles or D2 objects. If I'm not mistaken, the compiler should also inline the conversions, so you will not have any performance penalty for using them, instead of regular doubles. Regards, Markus. Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.