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This method is incidentally related to How to Set parts of indexed lists?

This method is incidentally related to How to Set parts of indexed lists?

This method is incidentally related to How to Set parts of indexed lists?

Perhaps though it would be better for these functions to ignore your construct rather than mutating it errantly.

Attributes[setDiscreteData] = HoldFirst; setDiscreteData[s_Symbol, rhs_] := With[{a := $DD[s]}, Set[s, new_] ^:= a = new; a = rhs;  Length[s] ^:= a // Query["tally", Tr, Last]; ] 

Perhaps it would be better for these functions to ignore your construct rather than mutating it errantly.

Attributes[setDiscreteData] = HoldFirst; setDiscreteData[s_Symbol, rhs_] := With[{a := $DD[s]}, a = rhs;  s=. ^:= (ClearAll[s]; a=.); Set[s, new_] ^:= a = new;  Length[s] ^:= a // Query["tally", Tr, Last]; ] 

The Symbol may be reset to normal (all definitions cleared) using Unset:

dd=.