hadley/evaluate — pull request #21 by lawremi (2012-10-20 13:32:38+00:00)
Title: Add print_visible argument. 

When FALSE, results of evaluation are returned as 'value' objects. This way, results can all be processed in sequence. The render callback approach, while convenient for some cases, was hobbled by its inability to integrate rendered results with input, conditions and graphics (not returned as a plot object).