C header file: tagged enumerations

[Kagamin via Digitalmars-d-learn]

On Thursday, 28 April 2016 at 22:54:10 UTC, Jesse Phillips wrote:
> This one doesn't get the values right for the different 
> versions. The other problem is functions are written as:
>
>    void* something(INSTALLMESSAGE arg);
>
> So I could make all the functions take an int/uint or such, but 
> that is a lot of change for the header along with less 
> documenting.

Different values depending on target version? That's weird, never 
seen anything like that in windows headers.

enum
{
// 12 others ...
	INSTALLMESSAGE_INITIALIZE     ,
	INSTALLMESSAGE_TERMINATE      ,
	INSTALLMESSAGE_SHOWDIALOG
}
static if(_WIN32_MSI >= 500)
enum
{
	INSTALLMESSAGE_PERFORMANCE=15,
	INSTALLMESSAGE_RMFILESINUSE
}
else static if(_WIN32_MSI >= 400)
enum INSTALLMESSAGE_RMFILESINUSE=15;
static if(_WIN32_MSI >= 450)
enum
{
	INSTALLMESSAGE_INSTALLSTART=INSTALLMESSAGE_RMFILESINUSE+1,
	INSTALLMESSAGE_INSTALLEND
}

alias INSTALLMESSAGE=int;