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--- | |
title: "Debugging" | |
--- | |
```{r echo = FALSE} | |
knitr::opts_chunk$set(collapse = TRUE, comment = "#>") | |
``` | |
Debugging methods in R6 classes is somewhat different from debugging normal R functions. | |
RStudio breakpoints don't work in R6 class methods. The simplest way to debug code is to insert a `browser()` line where you want to open a debugging console, reload the classes, and then step through your code. But this involves modifying your code, reloading it, and re-instantiating any objects you want to test. | |
## Enabling debugging for all future instances of a class | |
R6 generator objects have a method called `debug()` which will enable debugging for a method. This will affect all instances of the class that are created after the `debug()` is called. | |
```{r eval=FALSE} | |
# An example class | |
Simple <- R6Class("Simple", | |
public = list( | |
x = 10, | |
getx = function() self$x | |
) | |
) | |
# This will enable debugging the getx() method for objects of the 'Simple' | |
# class that are instantiated in the future. | |
Simple$debug("getx") | |
s <- Simple$new() | |
s$getx() | |
# [Debugging prompt] | |
``` | |
To disable debugging for future instances, use the generator's `undebug()` method: | |
```{r eval=FALSE} | |
# Disable debugging for future instances: | |
Simple$undebug("getx") | |
s <- Simple$new() | |
s$getx() | |
#> [1] 10 | |
``` | |
## Debugging methods in individual objects | |
To enable debugging for a method in a single instance of an object, use the `debug()` function (not the `debug()` method in the generator object). | |
```{r eval=FALSE} | |
s <- Simple$new() | |
debug(s$getx) | |
s$getx() | |
# [Debugging prompt] | |
``` | |
Use `undebug()` to disable debugging on an object's method. | |
```{r eval=FALSE} | |
undebug(s$getx) | |
s$getx() | |
#> [1] 10 | |
``` | |
You can also use the `trace()` function to specify where in a method you want to drop into the debugging console. |