How to get the symbol name of a list element?

Question

Let's say we have a list g with variable d as its element:

Clear[g, d]
g = {1,2,3,d}

Now g[[4]] evaluates to d. But after d is assigned, g[[4]] evaluates to d's value. But it seems like g[[4]] is still pointing to d:

In[48]:= d = 1

Out[48]= 1

In[49]:= g[[4]]

Out[49]= 1

In[50]:= d = 2

Out[50]= 2

In[51]:= g[[4]]

Out[51]= 2

So is there anyway to get the symbol of g[[4]]? SymbolName does not work in this case. SymbolName[g[[4]]] results in an error.

Answer 1

ClearAll[g, d]
g = {1, 2, 3, d}
Part[g, 4]  (* what you expect *)
Trace[Part[g, 4]] (* how it is produced *)
d = 4; (* assign value *)
Trace[Part[g, 4]]  (* now you get the evaluated part *)
OwnValues[g] // FullForm  (* examine the assignment result *)
Extract[%, {1, 2, 4}, HoldForm]  (* extract what you want *)

Answer 2

You can obtain the name using Hold

Clear[g, d]
g = {1, 2, 3, d};
d = 2;

o = OwnValues[g];
m = MapAll[Hold, o];
h = FirstCase[m, RuleDelayed[_, Hold[z_]] :> z, _, Infinity];
s = ToString[h[[4]]];
n = StringTake[s, {6, -2}]

"d"