ybj2004/wrapr

Wrap R Functions for Debugging and Ease of Use

This document describes wrapr, an R package available from Github and CRAN.

Introduction

wrapr wraps R functions debugging and better standard evaluation.

Primary wrapr services include:

• wrapr::let()
• wrapr::DebugFnW()

wrapr::let()

wrapr::let() allows execution of arbitrary code with substituted variable names (note this is subtly different than binding values for names as with base::substitute() or base::with()). Please see vignette('let', package='wrapr') for examples.

wrapr::DebugFnW()

wrapr::DebugFnW() wraps a function for debugging. If the function throws an exception the execution context (function arguments, function name, and more) is captured and stored for the user. The function call can then be reconstituted, inspected and even re-run with a step-debugger. Please see vignette('DebugFnW', package='wrapr') for examples.

dump.frames

Note: wrapr debug functionality rehashes some of the capabilities of dump.frames (see help(dump.frames)). Roughly dump.frames catches the exception (so trying to step or continue re-throws, and arguments may have moved from their starting values) and wrapr catches the call causing the exception in a state prior to starting the calculation (so arguments should be at their starting values). We have found some cases where wrapr is a bit more convenient in how it interacts with the RStudio visual debugger (please see this screencast for some comparison). Also, please see this article for use of tryCatch and withRestarts.