S3 classes and methods

library(sessioncheck)

The sessioncheck package is designed to be lightweight, and has no dependencies. It defines two S3 classes: the sessioncheck() function returns an object of class sessioncheck_sessioncheck and the individual check functions return objects of class sessioncheck_status.

pkg_status <- check_attached_packages(action = "none")
obj_status <- check_globalenv_objects(action = "none") 
session_check <- sessioncheck(action = "none")

class(pkg_status)
#> [1] "sessioncheck_status"
class(obj_status)
#> [1] "sessioncheck_status"
class(session_check)
#> [1] "sessioncheck_sessioncheck"

Both classes have a format() method and a print() method, and both are coercible to data frames via as.data.frame(). A brief discussion of these classes and methods is provided here.

sessioncheck_status objects

Internally, a sessioncheck_status object is a named list with two components:

• The status component is a named logical vector where names correspond to detected entities, and values that indicate whether an action is triggered by that entity. It is intended to be roughly analogous to an “exit status”: FALSE corresponds to exit status zero and no actions are triggered, TRUE is a non-zero exist status and actions can be taken.
• The type component is a string indicating which check function create the status object.

This is illustrated below:

unclass(pkg_status)
#> $status
#> sessioncheck        stats     graphics    grDevices        utils     datasets 
#>         TRUE        FALSE        FALSE        FALSE        FALSE        FALSE 
#>      methods         base 
#>        FALSE        FALSE 
#> 
#> $type
#> [1] "package"

The format() and print() methods for a sessioncheck_status object produce the text displayed to the user in any message, warning, or error:

print(pkg_status)
#> Attached packages: sessioncheck

As a convenience, an as.data.frame() method is also supplied:

as.data.frame(pkg_status)
#>      type       entity status
#> 1 package sessioncheck   TRUE
#> 2 package        stats  FALSE
#> 3 package     graphics  FALSE
#> 4 package    grDevices  FALSE
#> 5 package        utils  FALSE
#> 6 package     datasets  FALSE
#> 7 package      methods  FALSE
#> 8 package         base  FALSE

sessioncheck_sessioncheck objects

Because the sessioncheck() function can call multiple checks, the data structure it returns is slightly different. As illustrated below it is a named list of sessioncheck_status objects:

lapply(session_check, unclass)
#> $globalenv
#> $globalenv$status
#> .Random.seed   obj_status   pkg_status 
#>        FALSE         TRUE         TRUE 
#> 
#> $globalenv$type
#> [1] "globalenv"
#> 
#> 
#> $packages
#> $packages$status
#> sessioncheck        stats     graphics    grDevices        utils     datasets 
#>         TRUE        FALSE        FALSE        FALSE        FALSE        FALSE 
#>      methods         base 
#>        FALSE        FALSE 
#> 
#> $packages$type
#> [1] "package"
#> 
#> 
#> $attachments
#> $attachments$status
#>           .GlobalEnv package:sessioncheck        package:stats 
#>                FALSE                FALSE                FALSE 
#>     package:graphics    package:grDevices        package:utils 
#>                FALSE                FALSE                FALSE 
#>     package:datasets      package:methods            Autoloads 
#>                FALSE                FALSE                FALSE 
#>          tools:callr         package:base 
#>                FALSE                FALSE 
#> 
#> $attachments$type
#> [1] "attachment"

As before, the format() and print() methods are used to construct the text to be displayed to the user:

print(session_check)
#> Session check results:
#> - Objects in global environment: obj_status, pkg_status
#> - Attached packages: sessioncheck
#> - Attached environments: [no issues]

Similarly, there is an as.data.frame() method provided as a convenience:

as.data.frame(session_check)
#>          type               entity status
#> 1   globalenv         .Random.seed  FALSE
#> 2   globalenv           obj_status   TRUE
#> 3   globalenv           pkg_status   TRUE
#> 4     package         sessioncheck   TRUE
#> 5     package                stats  FALSE
#> 6     package             graphics  FALSE
#> 7     package            grDevices  FALSE
#> 8     package                utils  FALSE
#> 9     package             datasets  FALSE
#> 10    package              methods  FALSE
#> 11    package                 base  FALSE
#> 12 attachment           .GlobalEnv  FALSE
#> 13 attachment package:sessioncheck  FALSE
#> 14 attachment        package:stats  FALSE
#> 15 attachment     package:graphics  FALSE
#> 16 attachment    package:grDevices  FALSE
#> 17 attachment        package:utils  FALSE
#> 18 attachment     package:datasets  FALSE
#> 19 attachment      package:methods  FALSE
#> 20 attachment            Autoloads  FALSE
#> 21 attachment          tools:callr  FALSE
#> 22 attachment         package:base  FALSE