Defining Dates for CALCULATE using a parameter and DATESMTD

[Anonymous]

Metric Current Period = SWITCH('Period Selection'[Period Type Selected],
    1, CALCULATE(Transactions[Metric],
        DATESMTD(
        {
        [AsAtDate]
        })
    )
)
Error: Cannot find table ".

For the purposes of monthly reporting, I'm trying to define a range of dates to calculate a metric over. The visual will then show a single total for only that period selected. AsAtDate is a measure corresponding to the last day that the report is being made for. I think it's a problem with the way the Column/Single Column Table is being defined?

Can I use a Measure in this way?

[Greg_Deckler]

@Anonymous Tought to say, not sure I have enough context about the data and what you are doing. But I would love it if measures could return tables. Would really help cut down on repeating the same code in multiple places. 

[Greg_Deckler]

@Anonymous Probably not, measures can't return tables and DATESMTD wants a table of dates.

[Anonymous]

@Greg_Deckler 

Ok to a switched to filters in series for the date table and new measures AsAtYear, AsAtMonth, AsAtQuarter so they only need to be calculated once with data refresh.  I've got to wonder if there is a better way to do it that jumps out at you, considering I'm leaping sideways from my expectation that I could create a table from a measure, and still casting off the assumptions I had.

Thanks for your reply as well.