labeling - Adding a label to an expression result

To make my notebook easier to read for non-Mathematica literate colleagues (myself included), I'd like to have the output from an assignment expression look somewhat more obvious. Normally an expression assignment would look something like this:

In[1]= myVariable = 1 + 1

Out[1]= 2

But I'd like to get an output that looks more like:

Out[1]= myVariable = 2

I'm sure there are very convoluted ways to get this as an output but is there some really simple thing I can do so that the input is also still fairly easily readable without a heap of other commands wrapped around it?

Answer

Presuming you only want to this special output to come from computations that bind a variable to the value of the computation, here is one way it can be done by $Pre and $Post:

SetAttributes[saveSet, HoldAll];
saveSet[form : Set[var_, _]] := (lastSet = ToString@Unevaluated@var; form);
saveSet[form : ___] := (lastSet =.; form)


$Pre = saveSet;

$Post = (If[ValueQ@lastSet, Row[{lastSet, " = ", #}], #]) &;

After these definitions are evaluated, computations using Set (=) show up as:

y = 42^2 + 1

y = 1765

but other expression evaluations will printout normally:

x == y

False

The downside of this is that, when these definitions are in effect, % becomes unusable after a Set evaluation. Condsider

y = 42^2 + 1

y = 1765

% - 1

-1+y = 1765