Caching of Graph Graphics

Question

In this answer, Simon Woods concludes that when you display an expression with head graph more than once, something is getting stored somewhere. I looked into it too and found out this only happens if you tie the expression with head graph to a symbol. Evaluating the symbol a second time will no longer print messages and results of random numbers are the same. Consider this example

g=Graph[{1 -> 2, 2 -> 3, 3 -> 1}, 
   VertexShapeFunction -> ({Random[] // Hue, Disk[Print["VSF"]; #, 0.05]} &)]

--prints--> messages --displays-> a graph with pretty colors

g

--displays--> a graph with the same pretty colors (and does not print messages)

even though

g // FullForm // InputForm

returns

(*output*)
FullForm[Graph[{1, 2, 3}, {DirectedEdge[1, 2], DirectedEdge[2, 3], 
      DirectedEdge[3, 1]}, {VertexShapeFunction -> 
        {{Hue[Random[]], Disk[Print["VSF"]; #1, 0.05]} & }}]]

where we can see that the colors are supposed to be generated randomly by the option VertexShapeFunction.

However, after evaluating

ClearSystemCache[];

evaluating g will (almost almost surely ;) ) yield a graph with a new colors.

this Q&A seems related.

My question is: How can we turn off such caching?

We can find systemoptions having to do with Cache by evaluating

SystemOptions["Cache*"]

but setting all the rules of the form

"Cache"-> True

to

"Cache" -> False

does not change the way the graphics behave.

They do however influence the value of

Timing[N[Pi, 1000000]][[1]]

The SystemOptions can be set by evaluating

SetSystemOptions["CacheOptions" -> "Developer" -> "Cache" -> False];
SetSystemOptions["CacheOptions" -> "Numeric" -> "Cache" -> False];
SetSystemOptions[
  "CacheOptions" -> "ParametricFunction" -> "Cache" -> False];
SetSystemOptions["CacheOptions" -> "Quantity" -> "Cache" -> False];
SetSystemOptions["CacheOptions" -> "Symbolic" -> "Cache" -> False];

Answer 1

You can turn off caching in graphs by setting the system options:

SetSystemOptions["GraphOptions" -> "CacheResults" -> False]