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I have a very complex code in which I assign a value to an element of an array and then I reassign to it another one. A minimal example:
Clear[ggg];
t = {1, 2, 3};
s = {2, 5, 6};
Evaluate[ggg @@ t ] = 1;
Evaluate[ggg @@ s] = 2;
Evaluate[ggg @@ t ] = -1;
Evaluate[ggg @@ s] = 3;
and the error is
Set::setraw: Cannot assign to raw object 1.
Set::setraw: Cannot assign to raw object 2.
A solution may be to use Condition or If, but does there exist a command to force the new assignment?
You can use Inactive to reassign down values:
Clear[ggg];
t = {1,2,3};
s = {2,5,6};
Evaluate[ggg @@ t] = 1;
Evaluate[ggg @@ s] = 2;
Check initial values:
ggg[1,2,3]
ggg[2,5,6]
1
2
Reassign using Inactive:
Activate @ Inactive[Set][Inactive[ggg] @@ t, -1]
Activate @ Inactive[Set][Inactive[ggg] @@ s, 3]
-1
3
Check:
ggg[1,2,3]
ggg[2,5,6]
-1
3
ClearAll[t,s]before making new assignments? $\endgroup$ggg[Sequence @@ t] = -1; ggg[Sequence @@ s] = 3;. But I suspect that you'll want to do things a little more naturally, like makegggaListrather than assign itDownValuesas you are doing. $\endgroup$Evaluate[ggg@@t]=-1, the left hand side ofSetevaluates to1because you have already given it that value with the previous evaluations.Setrightly complains that it can't assign a value of-1to1. $\endgroup$