mjhjmtu

I have a code in which I define something like this:

cc[1, 2] = 1;
cc[2, 6] = 12;
cc[3, 7] = 3;

After some manipulation I define a sort of temporary variable related to cc:

cctemp[1, 2] = 13;
cctemp[2, 6] = 8;
cctemp[3, 7] = 4;
cctemp[1, 9] = 87;

There are new and old indices.

Now in my code i wanna replace cc with cctemp.
I can do the trivial assignment and i can use a Do for the substitution but its not the best. How could I realize the assignment ?

(Ps maybe something like Activate @ Inactive ....)

Thank you

DownValues[cc] = DownValues[cctemp] /. cctemp -> cc;
cc[1, 9]

87

cc[1, 2]

13

If cc has some assignments that are not overridden by the assignments in cctemp you can use

DownValues[cc] = DeleteDuplicatesBy[
 Join[DownValues[cctemp], DownValues[cc]] /. cctemp -> cc, #[[1,1]]&]

You can make use of the undocumented Language`ExtendedDefinition function that underlies the Wolfram Cloud. Suppose:

cctemp[1,2] = 13;
cctemp[2,6] = 8;
cctemp[3,7] = 4;
cctemp[1,9] = 87;

Then:

Language`ExtendedDefiniition[cc] = Language`ExtendedDefinition[cctemp] /. cctemp -> cc;

Finally:

DownValues[cc]

HoldPattern[cc[1, 2]] :> 13, HoldPattern[cc[1, 9]] :> 87,
HoldPattern[cc[2, 6]] :> 8, HoldPattern[cc[3, 7]] :> 4