Evaluation context inside FILTER

[SuraMan]

Hello,

I have a question about how evaluation takes place in the code snippet below. This filter() returns all the dates in 'Date'[Date] which are equal or less than the highest date in the current filter context.

FILTER ( 
        ALL ( ‘Date’[Date] ), 
        ‘Date’[Date] <= MAX( ‘Date’[Date] ) 
    ) 

My question is, since ALL() removes any filters on 'Date'[Date] above, why does MAX(‘Date’[Date])  not return the last date in the full table 'Date'[Date], ignoring the current filter context?

For the above code to work as intended, MAX( ‘Date’[Date] ) has to be evaluated in the original filter context disregarding the effects of ALL(), however, it is not clear to me what rules determine that MAX() has to be evaluated in that manner.

If we look at the third line; it looks like ‘Date’[Date] evaluates in ALL() context while MAX(‘Date’[Date]) evaluates in the original context. Two different evaluation contexts for the two references of ‘Date’[Date] in the same line!

If you can clarify this, that would be wonderful.

[Zubair_Muhammad · Accepted solution]

@SuraMan 

I believe the rule to remember is that
Inside a MEASURE

1) Expressions like SUM,MAX will always respond to available FILTER CONTEXT
Since FILTER is only an iterator and introduces ROW CONTEXT only,    MAX( ‘Date’[Date] ) responds to the FILTER context of the VISUAL (Matrix, Table, chart etc) which you are using.
If you use CALCULATE(MAX( ‘Date’[Date] )), we should get different results because in that case it will transform the ROW CONTEXT introduced by FILTER function into FILTER CONTEXT.
2) Naked column references (TableName[ColumnName]) inside an INTERATOR like FILTER,SUMX,MAXX will refer to ROW CONTEXT of that ITERATOR

[SuraMan]

Thanks @Zubair_Muhammad  for the explanation