Hello Joost,
> I'd like to have one unique stream to write to. I could make a
> ClassMethod Write(data As %String), but then I need a ClassProperty
> out As %AbstractStream or something to write to. A global variable (=
> unique, and available in every object) would do the trick, too.
>
> How can I specify something like that?
>
> For more information: This is the Singleton programming pattern, see
> http://www.campusprogram.com/reference/en/wikipedia/s/si/singleton_patt
> ern.html
if the stream should be process-global, you can set a %-variable.
But shouldn't access it directly, because it have to be set before.
I use a macro to access a singleton.
#define $$$UniqueStream ##class(SinletonManager).GetUniqueStream()
It works like a GetMethod of an object-property.
Class SingletonManager {
ClassMethod GetUniqueStream() as UniqueStream
{
s:'$d(%uniqueStream) %uniqueStream=##class(UniqueStream).%New()
q %uniqueStream
}
}
If you want a system-wide singleton, you should make the singleton
persistent and save the OID.
But then you have to open it on every access and must synchronize the
write-access on it, or use a background-process that manages it...
HTH
^Florian
