• ← $Post
• → $PrePrint

$Pre

WMA

$Pre

is a global variable whose value, if set, is applied to every input expression.

Set Timing as the $Pre function, stores the elapsed time in a variable,
stores just the result in Out[$Line] and print a formatted version showing the elapsed time

• • $Pre := (Print["[Processing input...]"];#1)&

• • $Post := (Print["[Storing result...]"]; #1)&

• • $PrePrint := (Print["The result is:"]; {TimeUsed[], #1})&

• • 2 + 2

• • $Pre = .; $Post = .;  $PrePrint = .;  $ElapsedTime = .;

• • 2 + 2