Interpretation
Wolfram Kernel
Make a formatting structure whose interpretation is not based on its appearance
Interpretation[display_, expr_]where display will be shown in the output cell, instead of expr, keeping expr for the evaluation.
By the default Interpretation applies MakeBoxes with StandardForm to display expression before printing it to an output cell
Example
Have a look at the following example
Interpretation[Red, 1]
(*VB[*)(1)(*,*)(*"1:eJxTTMoPSmNiYGAo5gISrimZJflFYZmp5cFdQK6GVphTtJamRpC7k3N+Tn5RtKGOggEQxWpqaOkAxbWUDK1SvSpCQnzzA4Jz/TIj3R3zTdNDgyOjcgtMg80KKtNy3DKDI0yDkl2LA5088kwCnAP93BMDAxxTA509vIyTi80DKoMtCiPTnV1c9KMCndJ9XfIcXR1NMkMDgtJtbZVAdsSGOWlpQpzIAiSCSnNSgzlAjNTEFP+8nEqwaEhRaSoAIuc3cA=="*)(*]VB*) + 1
2You can create custom output form for certain symbols:
vec2 /: MakeBoxes[v: vec2[x_,y_], StandardForm] := With[{i = Interpretation[Row[{Hue[(*SpB[*)Power[Sin[x](*|*),(*|*)2](*]SpB*)], Hue[(*SpB[*)Power[Sin[y](*|*),(*|*)2](*]SpB*)]}]//Panel, v]},
MakeBoxes[i, StandardForm]
]
Now if we evaluate this:
vec2[0.4,0.2]
(*VB[*)(vec2[0.4, 0.2])(*,*)(*"1:eJy1kcFugkAURWnTRdO/qCtEU0EZlCZdDMhIbbTAoAjGBepIUUAUiVDrt/ZXitqk6aa7bu67977FO8m7n66NxTVFUcldIcrc3623Q5/s8ecVRdGMJI2ZMq25EQnGNNM5pcOBZobnWk3JmH3gACfwgsCDRl3guWZjUqaZarFlStwj6Wam2VtrOOz7dgeugTfAthPGAAtxvgiQj0fAmCmJLqkRr8l6v+PqGiS6rHYbs6Sp5bi1sT253a45CLU4K67kxsJKNGQhD0LoLrL+W+l0azKUTuODKVfP+huRbYi8IAK2LootAJo8EP4LUjbRFKFV+30XtA3DsyGMaspy9fQDeTwWplOYvxFmGA5GwHFW8QZHFQlbTmUUIdfee/KQ9xTHdaxUwGGcXQAzsycHL27YJS4U1S70sYyjPvZYpbcUTQU96zJUwQax7DeKVBBc/n5TiJEGBN+eDHHnr1GQn1tzm5Iv+HGbcQ=="*)(*]VB*)
(*VB[*)(vec2[0.4, 0.2])(*,*)(*"1:eJy1kcFugkAURWnTRdO/qCtEU0EZlCZdDMhIbbTAoAjGBepIUUAUiVDrt/ZXitqk6aa7bu67977FO8m7n66NxTVFUcldIcrc3623Q5/s8ecVRdGMJI2ZMq25EQnGNNM5pcOBZobnWk3JmH3gACfwgsCDRl3guWZjUqaZarFlStwj6Wam2VtrOOz7dgeugTfAthPGAAtxvgiQj0fAmCmJLqkRr8l6v+PqGiS6rHYbs6Sp5bi1sT253a45CLU4K67kxsJKNGQhD0LoLrL+W+l0azKUTuODKVfP+huRbYi8IAK2LootAJo8EP4LUjbRFKFV+30XtA3DsyGMaspy9fQDeTwWplOYvxFmGA5GwHFW8QZHFQlbTmUUIdfee/KQ9xTHdaxUwGGcXQAzsycHL27YJS4U1S70sYyjPvZYpbcUTQU96zJUwQax7DeKVBBc/n5TiJEGBN+eDHHnr1GQn1tzm5Iv+HGbcQ=="*)(*]VB*)[[1]]
0.4