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Question Julius Kavay · Apr 29

What is the REAL content of $THIS (because it seems, $THIS is not always the expected $THIS)?

According to documentation, quotation: "$THIS contains the current class context.
The class context for an instance method is the current object reference (OREF).
The class context for a class method is the current classname as a string value."

As my example below shows, either the documentation or the implementation (or both) is wrong, I always call a class method (Value) and expected the class name as the return value but got either the class name or an OREF. Moreover, if I repeat the call, I get another values. But why?
Does anyone have a clear explanation (for an aging brain) or have I misunderstood something?

Class DC.ValueOfThis Extends%RegisteredObject
{

ClassMethod Test()
{
	write$zv,!!
	set obj=..%New()
	do obj.Work()
	write"From classmethod: ",$this," ",$this," ",..Value()," ",..Value()," ",..Value()," ",$this,!
	do obj.Work()
}

Method Work()
{
	write"From inst.method: ",$this," ",$this," ",..Value()," ",..Value()," ",..Value()," ",$this,!
}

ClassMethod Value()
{
	quit$this
}

}

And the test output is:

USER>

USER>d##class(DC.ValueOfThis).Test()
IRIS for UNIX (Ubuntu Server LTS for x86-64) 2021.2 (Build 649U) Thu Jan 20202208:49:51 EST

From inst.method: 1@DC.ValueOfThis 1@DC.ValueOfThis DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis
From classmethod: DC.ValueOfThis DC.ValueOfThis DC.ValueOfThis DC.ValueOfThis DC.ValueOfThis DC.ValueOfThis
From inst.method: 1@DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis 1@DC.ValueOfThis

USER>

Product version: IRIS 2021.2

Discussion (0)0

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Comments

Eduard Lebedyuk · May 1

Looks like a bug. Please check with WRC.

Simplified your example a bit:

Class DC.ValueOfThis Extends%RegisteredObject
{

/// do ##class(DC.ValueOfThis).Test()ClassMethod Test()
{
	write$zv,!!
	set obj=..%New()
	do obj.Work()
	write$$$FormatText("classmethod: $this %1, ..Value() %2", $this, ..Value()),!
	do obj.Work()
}

Method Work()
{
	write$$$FormatText("method: $this %1, ..Value() %2", $this, ..Value()),!
}

ClassMethod Value()
{
	quit$this
}

}

0 0

Joel Solon · May 2

Are you asking this out of curiosity? Or is there another reason for the question? How would you like to use $this?

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Julius Kavay May 5 to Joel Solon

I had a real use case, where from an instance method a class method was called and that class method used $this as argument in a subsequent call. In the very first call the content of $this was the class name (as documented) but in subsequent calls it contained the OREF and that caused a <CLASS DOES NOT EXIST> error. A WRC ticket is already open.

0 0

Julius Kavay · May 12

Right now the WRC told me, the problem is corrected

0 0