Singleton pattern template

Singleton pattern for single user session (process execution):
class VKSingletonTest
{
    private int rand;

    public static VKSingletonTest instance()
    {
        const str   mySysGlobalCacheKey   = 'VKSingletonTest';
        VKSingletonTest singleton;
        // AX2012
        //SysGlobalCache  globalCache = infolog.objectOnServer() ? appl.globalCache() : infolog.globalCache();
        // AX7/d365
        SysGlobalCache  globalCache = appl.globalCache();
 
        if (globalCache.isSet(classStr(VKSingletonTest), mySysGlobalCacheKey))
        {
            Info('cached instance');
            singleton = globalCache.get(classStr(VKSingletonTest), mySysGlobalCacheKey);
        }
        else
        {
            Info('new instance');
            singleton = new VKSingletonTest();
            //  Additional line for AX2012
            //globalCache.set(classStr(SingletonClass), mySysGlobalCacheKey, singleton);
            globalCache.set(classStr(VKSingletonTest), mySysGlobalCacheKey, singleton);
        }
 
        return singleton;
    }

    protected void new()
    {
        Random Random = new Random();
        rand = Random.nextInt();
    }

    public int getRand()
    {
        return rand;
    }

}
Simplified for D365F&SCM:
class VKSingletonTest
{
    private static VKSingletonTest singleton = new VKSingletonTest();
    private int rand;

    public static VKSingletonTest instance()
    {
        return singleton;
    }

    protected void new()
    {
        Random Random = new Random();
        rand = Random.nextInt();
    }

    public int getRand()
    {
        return rand;
    }
}
Test:
class VKTest
{
    public static void main(Args _args)
    {
        VKSingletonTest singleton = VKSingletonTest::instance();
        info(strFmt("%1", singleton.getRand()));

        singleton = VKSingletonTest::instance();
        info(strFmt("%1", singleton.getRand()));
    }
}
Both numbers will be the same in a single execution. However, for the next job execution numbers will be different.
SysGlobalObjectCache is server-shared caching across all user sessions on a specific server.
Single SysGlobalObjectCache exists for each server instance and is shared for all sessions.
class VKSingletonTest
{
    private int rand;
    #define.CurrentVersion(1)
    #localMacro.CurrentList
        rand
    #endmacro

    public static VKSingletonTest instance()
    {
        const str               myScopeKey  = 'VKSingletonTest';
        container               cacheKey    = ['VKSingletonTest'];
        container               cacheValue;
        VKSingletonTest         singleton;
        SysGlobalObjectCache    globalCache = new SysGlobalObjectCache();

        cacheValue = globalCache.find(myScopeKey, cacheKey);
 
        if (cacheValue == conNull())
        {
            Info('new instance');
            singleton = new VKSingletonTest();
            globalCache.insert(myScopeKey, cacheKey, singleton.pack());
        }
        else
        {
            Info('cached instance');
            singleton = new VKSingletonTest();
            singleton.unpack(cacheValue);
        }
 
        return singleton;
    }

    protected void new()
    {
        Random Random = new Random();
        rand = Random.nextInt();
    }

    public int getRand()
    {
        return rand;
    }

    public container pack()
    {
        return [#CurrentVersion, #CurrentList];
    }

    public boolean unpack(container packedClass)
    {
        Version version = RunBase::getVersion(packedClass);
 
        switch (version)
        {
            case #CurrentVersion:
                [version, #CurrentList] =  packedClass;
                break;
 
            default:
                return false;
        }
 
        return true;
    }

}
Standard example with caching values in CustVendExternalItemDescription class.

All entries in SysGlobalObjectCache can be removed for by running a class that uses the following URL:

/?mi=SysClassRunner&cls=SysFlushAOD.

The SysFlushAOD class clears all cache in SysGlobalObjectCache.

System administration / Setup / Refresh elements


 

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