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Diffstat (limited to 'ACE/contrib/utility/Documentation/Thoughts/Enum/EnumInfo')
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diff --git a/ACE/contrib/utility/Documentation/Thoughts/Enum/EnumInfo b/ACE/contrib/utility/Documentation/Thoughts/Enum/EnumInfo new file mode 100644 index 00000000000..e59a27c0820 --- /dev/null +++ b/ACE/contrib/utility/Documentation/Thoughts/Enum/EnumInfo @@ -0,0 +1,45 @@ +From: "Klaus Eichner" <klaus_gb@yahoo.com> +Date: Sat, 26 Jul 2003 14:53:23 +0100 +Newsgroups: comp.lang.c++ +Subject: Re: enum count + +"Clive" <clive@clive.clive> wrote in message +news:3f21e5cc$0$23611$5a62ac22@freenews.iinet.net.au... +> If you have an enum, is there any way during execution to find the number +of +> values in the enum? +> Say I have, +> +> enum great { five, ten, fifteen }; +> +> How could I get the number 3 from that? + +You could get the number 3 from 'great' with your own, user-defined +'Enum_Info' template: + +cout << "The number of values in enum great is " + << Enum_Info<great>::number_of_elements + << endl; + +The 'Enum_Info' template is defined as follows. +Suppose you have the following enums: + +enum great { five, ten, fifteen }; +enum greater { none, one, fourtytwo, fourtythree, fourtyfour }; +enum even_greater { minusone, minustwo, minusthree, minusfour, minusfive, +minussix, minusseven }; + +You could build a template class 'Enum_Info' which uses specialisation to +register the number of elements in each enum + +template <class T> class Enum_Info { }; +template <> class Enum_Info<great> { static const int number_of_elements = +3; }; +template <> class Enum_Info<greater> { static const int number_of_elements = +5; }; +template <> class Enum_Info<even_greater> { static const int +number_of_elements = 7; }; + + + +$Id$ |