Not sure what is GridExpression, but at first quick glance (thanks, Greg) I think you need to use safe select approach instead of blanking record source.

>Oops..
>
>That is returning it with the root being the form name, and for some reason THAT is failing when used in a EVALUATE call.
>
>It returns
> "formquote.pageframe1.pageMtlSummary.grid1"
>
>but, when I pass that through Evalulate("formquote.pageframe1.pageMtlSummary.grid1"), it does not resolve it. It says "object formquote is not found."
>
>If the root is ThisForm it does work, but that is not what the sys() method returns.
>
>If I pass "thisform.pageframe1.pageMtlSummary.grid1" into Eval, it works fine.
>
>I tried '_screen.'+sys(1272,loGrid) and '_vfp.'+sys(1272,loGrid)' but that did not work either.
>
>The GridExtra.Setup() does an eval on GridExtra.GridExpression, and that is where it fails.
>It seems to want 'thisform.PageFrame1.PageMtlSummary.Grid1', which I previously was hard-coding, not 'formquote.pageframe1.pageMtlSummary.grid1'. You can see that I am trying to refactor the grid reference to one place at the top of the code.
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>
>Here is the code from the Activate() event on the Page:
>

>Local lcAlias
>
> Dodefault()
>
> lcAlias='csrSummaryMtl'
> loGrid=this.oLineItemsGrid
>
> *-- Do we need to fetch the rocords, or do we already have them?
> If thisform.lMtlSummaryCursorReady=.f.
>  *-- Clear grid, get data, setup grid ---
>  loGrid.RecordSource=''
>  thisform.getSummaryMtlRecords(QuoteInf.quote_no, lcAlias)
>  loGrid.RecordSource=lcAlias
>  loGrid.set_header_captions()
>  loGrid.AutoFit()
>  thisform.lMtlSummaryCursorReady=.t.
>
>  *-- Setup GridExtra to work with grid above ----------
>  Iif(PemStatus(this, 'GridExtra', 5), this.RemoveObject('GridExtra'), null)
>  loGridExtra=this.AddObject('GridExtra', 'GridExtra')
>  this.GridExtra.GridExpression=Sys(1272,loGrid)
>  this.GridExtra.setup()
> endif
> 
> thisform.calcSummaryMtl(lcAlias) && Recalculate in case a filter has been set on the records.
>
> thisform.Refresh()
>
>

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>>>How can I get the fully qualified object name from reference to the object?
>>>
>>>For instance a Grid on a Page in a PageFrame on a Form...
>>>
>>>So in a method on the Grid, I can just use 'this.', but this full object heirachy is ''thisform.pageframe1.pageMtlSummary.grid1'
>>>
>>>How can I resolve the full path name from just the object reference?
>>
>>sys(1272)