[OASIS Issue Tracker] Commented: (ODATA-395) Simplify rule for implicit values of enumeration members

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

    [ http://tools.oasis-open.org/issues/browse/ODATA-395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=33454#action_33454 ] 

Stefan Drees commented on ODATA-395:
------------------------------------

So as runnable c++ code:

#include <iostream>
enum ShippingMethod {
    VIP,
    FirstClass,
    TwoDay = 0,
    Overnight
};
int main()
{
    ShippingMethod shipMe = TwoDay;
    std::cout << " VIP = " << VIP << ", FirstClass = "
              << FirstClass << ", TwoDay = " << shipMe
              << ", and Overnight = " << Overnight << '\n';
}

the execution should yield:

 VIP = 0, FirstClass = 1, TwoDay = 0, and Overnight = 1

and does so.

Although I might already be included inside the "we" of the descriptions four-valued last sentence ;-) why not stating it explicitly:

I second the proposal even in c/c++ code I personally consider it good style to either let the compiler decide on or to explicitly set all values. 
The latter is triggered quite often, when interfacing to pre-existing sets of constants (where gaps are present).


> Simplify rule for implicit values of enumeration members
> --------------------------------------------------------
>
>                 Key: ODATA-395
>                 URL: http://tools.oasis-open.org/issues/browse/ODATA-395
>             Project: OASIS Open Data Protocol (OData) TC
>          Issue Type: Improvement
>          Components: OData CSDL
>    Affects Versions: V4.0_CSD01
>         Environment: [Proposed]
>            Reporter: Ralf Handl
>             Fix For: V4.0_CSD02
>
>
> Enumeration members have an optional Value attribute for specifying an integer equivalent to the symbolic member name that is for ordering.
> The current rule for implicitly numbering the enumeration members is cloned from the C family of programming languages and allows specifying values for some members while having the other members being numbered implicitly. This can lead to surprising results for the uninitiated:
> <EnumType Name="ShippingMethod">
>   <Member Name="VIP"/>
>   <Member Name="FirstClass"/>
>   <Member Name="TwoDay" Value="0"/>
>   <Member Name="Overnight"/>
> </EnumType>
> The result is that both VIP and TwoDay get the value zero and both FirstClass and Overnight get the value 1.
> While we see value in having Value optional, we see no value in providing a value for some members only.

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