Indirection (@) issues

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Jim Self

>Kevin wrote: >I posted about this once before, and it seems that someone had an >answer. But I can't find that post now. That was me. It was in response to Nancy's question about indirection. >I am trying to use indirection (@) to execute a callback function. >But it looks like the indirection is limited to 8 characters. The form of indirection you are trying is not standard nor is it supported by GT.M. > >e.g. > >GTM>w $$SIMPLE^TMGTEST("hello") >You said:hello >GTM>set x="SIMPLE^TMGTEST" > >GTM>w $$@x@("hello") >%GTM-E-LABELMISSING, Label referenced but not defined: SIMPLE^T > >GTM> > > >How should I do this? Try putting the "$$" inside the quotes.

I don't think this is standard either (or documented in GT.M for that matter), but this works for me.

s test="$$ucase^%zString" w @test@("hello kevin") HELLO KEVIN

Jim Self Gregory wrote: >the syntax you were trying to use is subscript indirection. It >is used to access arrays when the array name and subscript (or >subscripts) are stored in variables. Though there is a surface >similarity between this syntax and that used to invoke an extrinsic >function, function calls and array references are very different >things in MUMPS.

Right. That is why I was suprised to find that it works at all in GT.M. Did you try it in Cache' or MUMPS_V1 or MSM?

hmmm. I just tried another test with disappointing (but not unexpected) results.

s func="$$ucase^%zString" s Y=@func@("hello kevin") w Y

That gives an error - variable expected in this context. However, the following does work.

s func="$$ucase^%zString" s @("Y="_func)@("hello kevin") w Y

The key in the examples I have tried seems to be that (in GT.M at least) if you start out with a standard form of indirection, such as argument indirection, then you can use the second @ to append subscripts or arguments to functions or subroutines.