I want to let the user define the variables on a plot with a vector. The problem is that the plot doesn't show if I use the coordinates of the vector

Question

I have a user-defined vector par={b,d}. Also, I have a user-defined function f(b,d). What I would like to do is to plot the expression f(b,d)=0 and label the axes with the corresponding names of the parameters. Up until now, I have tried this:

ContourPlot[f[b,d] == 0, {par[[1]], 0, 4}, {par[[2]], 0, 6}, 
  FrameLabel -> {ToString[par[[1]]], ToString[par[[2]]]}]

but I am getting the following error:

Answer 1

Use Evaluate.

par = {b, d};
f[x_, y_] = x^2 + y^2 - 1;
ContourPlot[
 f[b, d] == 0, {par[[1]], 0, 4} // Evaluate, {par[[2]], 0, 6} // 
  Evaluate, FrameLabel -> {ToString[par[[1]]], ToString[par[[2]]]}]