I'm quite shure, the above code won't work as expected, or with the words of Joseph Weizenbaum: “A computer will do what you tell it to do, but that may be much different from what you had in mind.”

The content of your myf variable is always 0 (the result of comparing nullstring with a filename), the size of tmpFile stream is also 0 (you never write into the stream).

Sometimes it's faster to write a "oneliner" to solve a simple problem then searching and downloading a solution from openexchange or from whereever... That's the beauty of the ObjectScript.

And if you think, the oneliner is worth to be reused, then make it to a method, add some small adjustments for a general usability...

The oneliner

s str="",tmp=##class(%File).TempFilename("txt") o tmp:"NWRU":0 i $t { u tmp zw ^||fruit s s=$zpos r:'$zseek(0) str#s c tmp:"D" }

The more general version

ClassMethod ToString(ref,max=32000)
{
    s tmp=##class(%File).TempFilename("txt") o tmp:"NWRU":0 q:'$t ""
    u tmp zw @ref s siz=$zpos r:'$zseek(0) str#$s(siz>max:max,1:siz) c tmp:"D" q str
}

Use it as

write ##(your.class).ToString($na(^||fruit))

First, disable the start of %ZSTART:

ManagementPortal-->SystemAdmin-->Configuration-->AdditionalSettings-->Startup:

here, set SystemStart to false.

Now, you can (Re)Start the system and check the %ZSTART routine.  <DIRECTORY> means, trying to access a nonexistent database directory.

After solving the problem, set SystemStart to true.

The simplest way is to create a classmethod, which returns the desired name:

Class DC.Evgenys.Data Extends %Persistent
{
/// which: 0=Fullname, 1=Schemaname, 2=Tablename
ClassMethod TableName(which = 0) [ CodeMode = objectgenerator ]
{
    set sch=%compiledclass.SqlSchemaName, tab=%compiledclass.SqlTableName
    do %code.WriteLine($c(9)_"quit $p("""_sch_"."_tab_","_sch_","_tab_""","","",which+1)")
    quit $$$OK
}
}

So you can do something like this:

for i=0:1:2 write ##class(DC.Evgenys.Data).TableName(i),!
DC_Evgenys.Data
DC_Evgenys
Data

You forgot to take into account the $system.SQL.* variants . They make much more fun, especially because you get time for a coffee break... 

Class My.Class 
{
Property MyProperty As %String [ReadOnly];

Method %OnNew(init As %String) As %Status [ Private, ServerOnly = 1 ]
{
    set i%MyProperty = init
}
} 

And use it as

set obj = ##class(My.Class).%New("Some initial value")
write obj.MyProperty --> Some initial value
set obj.MyProperty --> <CANNOT SET THIS PROPERTY>

A possible work-around could be the class below. In short, you work with your json property as intended, merely before saving the object, you save the json-property into a stream and after opening an instance, you restore the json-property from the the stream - that's all. The drawback, no SQL over the json property...

Class DC.Dyn Extends %Persistent
{
Property json As %DynamicObject [ Transient ];
Property jstr As %GlobalCharacterStream [ Internal, Private ];

ClassMethod MyTest(kill = 0)
{
   if kill do ..%KillExtent(1,1)

   set obj=..%New()
   set obj.json.short="A short test text"
   set obj.json.maxstr=$tr($j("",$$$MaxStringLength)," ","X")
   do obj.json.%Set("hugedata",..stream(obj),"stream")

   write "Status : ",obj.%Save(),!
   set id=obj.%Id()
   write "ID : ",id,!
   kill (id)

   set obj=..%OpenId(id)
   write "short : ",obj.json.short,!
   write "maxstr : ",$e(obj.json.maxstr,1,20),"... Size: ",$length(obj.json.maxstr),!
   set stream=obj.json.%Get("hugedata",,"stream")
   write "hugedata: ",stream.Read(20),"... Size: ",stream.Size,!
}

ClassMethod stream(obj)
{
   set stream=##class(%Stream.TmpCharacter).%New()
   do stream.Write(obj.json.short)
   do stream.Write(obj.json.maxstr)
   do stream.Write(obj.json.maxstr)
   quit stream
}

Method %OnOpen() As %Status [ Private, ServerOnly = 1 ]
{
   if ..jstr {
      do ..jstr.Rewind()
      set ..json=##class(%DynamicAbstractObject).%FromJSON(..jstr)
   }
   Quit $$$OK
}

Method %OnAddToSaveSet(depth As %Integer = 3, insert As %Integer = 0, callcount As %Integer = 0) As %Status [ Private, ServerOnly = 1 ]
{
   do ..jstr.Clear(), ..json.%ToJSON(..jstr)
   Quit $$$OK
}
}

Some testing...

IDEV:USER>d ##class(DC.Dyn).MyTest(1)
Status  : 1
ID      : 1
short   : A short test text
maxstr  : XXXXXXXXXXXXXXXXXXXX... Size: 3641144
hugedata: A short test textXXX... Size: 7282305

If your code uses obj.%Reload() then %OnReload() and %OnOpen() should contain the same code.

Your solution is just perfect. And fast.

But yes, you can avoid string manipulations... This one, for example, uses math only, merely it's neither short nor looks elegant:

 set dt=$h write $zd(dt,8)*100+($p(dt,",",2)\3600)*100+($p(dt,",",2)#3600\60)*100+($p(dt,",",2)#60)

but gives the same result as your short and nice solution...

 set dt=$h write $zd(dt,8)*100+($p(dt,",",2)\3600)*100+($p(dt,",",2)#3600\60)*100+($p(dt,",",2)#60),!,$tr($zdt(dt,8)," :")

On the other hand, you can install new brakes on your car, as suggested by others... ;-))

Just compare those codes with yours:

set h=$h, t=$zh for i=1:1:1E6 { set x=$tr($system.SQL.TOCHAR($h,"YYYY^MM^DD^HH24^MI^SS"),"^") } write $zh-t,!

set h=$h, t=$zh for i=1:1:1E6 { set x=$tr($zdt(h,8)," :") } write $zh-t,!

The choice is yours...

- Use stream instead of string or

- shorten the data... ;-))

On ShadowServer,  namespace %SYS

do ^SHADOW

then option 4 or 11

A simple

write ##class(%SYS.Namespace).GetPackageDest(yourNsp, yourPackage)

should do the trick

The same goes for globals and routines

write ##class(%SYS.Namespace).GetGlobalDest(yourNsp, yourPackage)

write ##class(%SYS.Namespace).GetRoutineDest(yourNsp, yourPackage)

if yourNsp is not provided, the current Nsp will be used