This only applies to the base python repl, everything works in IPython repls.

In discussion on b2fbae7 discovered that sys.displayhook only gets evaluated for expressions, not statements.

This means that things like

import numpy
pass
a = b

will not trigger the auto-redrawing. This is particularly troubling because this mean

ln, = ax.plot(...)

will not trigger a re-draw, but

ax.plot(...)

will.

Due to b2fbae7, where we rely on the auto-redrawing to trigger the pyplot redrawing this means that many pyplot workflows in the normal repl are broken (as in things that used to auto-redraw no longer do).

The options I think are:

1. figure out how to trigger a call back on statements (if this is possible, it is well hidden. There may be a reason IPython completely re-wrote the execution handling)
2. say we only support interactive plotting with the IPython repl (which is a major regression)
3. revert the removal of draw_if_interactive which maintains some functions as 'special'

I suspect that the answer is going to be both 2 and 3. normal python shell keeps current functionality and gains some new functionality, IPython picks up lots of new functionality, and the code base keeps this particular wart.