Package 'globals'

Title: Identify Global Objects in R Expressions
Description: Identifies global ("unknown" or "free") objects in R expressions by code inspection using various strategies (ordered, liberal, or conservative). The objective of this package is to make it as simple as possible to identify global objects for the purpose of exporting them in parallel, distributed compute environments.
Authors: Henrik Bengtsson [aut, cre, cph], Davis Vaughan [ctb]
Maintainer: Henrik Bengtsson <[email protected]>
License: LGPL (>= 2.1)
Version: 0.16.2
Built: 2024-07-13 02:45:22 UTC
Source: https://github.com/HenrikBengtsson/globals

Help Index


Drop certain types of globals

Description

Drop certain types of globals

Usage

## S3 method for class 'Globals'
cleanup(globals, drop = c("missing", "base-packages", "nativesymbolinfo"), ...)

Arguments

globals

A Globals object.

drop

A character vector specifying what type of globals to drop.

...

Not used


Get all global objects of an expression

Description

Get all global objects of an expression

Usage

findGlobals(
  expr,
  envir = parent.frame(),
  ...,
  attributes = TRUE,
  tweak = NULL,
  dotdotdot = c("warning", "error", "return", "ignore"),
  method = c("ordered", "conservative", "liberal"),
  substitute = FALSE,
  unlist = TRUE,
  trace = FALSE
)

globalsOf(
  expr,
  envir = parent.frame(),
  ...,
  method = c("ordered", "conservative", "liberal"),
  tweak = NULL,
  locals = NA,
  substitute = FALSE,
  mustExist = TRUE,
  unlist = TRUE,
  recursive = TRUE,
  skip = NULL
)

Arguments

expr

An R expression.

envir

The environment from where to search for globals.

...

Not used.

attributes

If TRUE (default), attributes of 'expr' are also searched. If FALSE, they are not. If a character vector, then attributes with matching names are searched. Note, the attributes of the attributes elements are not searched, that is, attributes are not searched recursively. Also, attributes are searched with 'dotdotdot = "ignore".

tweak

An optional function that takes an expression and returns a tweaked expression.

dotdotdot

TBD.

method

A character string specifying what type of search algorithm to use.

substitute

If TRUE, the expression is substitute():ed, otherwise not.

unlist

If TRUE, a list of unique objects is returned. If FALSE, a list of length(expr) sublists.

trace

TBD.

locals

Should globals part of any "local" environment of a function be included or not?

mustExist

If TRUE, an error is thrown if the object of the identified global cannot be located. Otherwise, the global is not returned.

recursive

If TRUE, globals that are closures (functions) and that exist outside of namespaces ("packages"), will be recursively scanned for globals.

skip

(internal) A list of globals not to be searched for additional globals. Ignored unless recursive is TRUE.

Details

There currently three strategies for identifying global objects.

The method = "ordered" search method identifies globals such that a global variable preceding a local variable with the same name is not dropped (which the "conservative" method would).

The method = "conservative" search method tries to keep the number of false positive to a minimum, i.e. the identified objects are most likely true global objects. At the same time, there is a risk that some true globals are not identified (see example). This search method returns the exact same result as the findGlobals() function of the codetools package.

The method = "liberal" search method tries to keep the true-positive ratio as high as possible, i.e. the true globals are most likely among the identified ones. At the same time, there is a risk that some false positives are also identified.

With recursive = TRUE, globals part of locally defined functions will also be found, otherwise not.

Value

findGlobals() returns a character vector.

globalsOf() returns a Globals object.

See Also

Internally, the codetools package is utilized for code inspections.

Examples

b <- 2
expr <- substitute({ a <- b; b <- 1 })

## Will _not_ identify 'b' (because it's also a local)
globalsC <- globalsOf(expr, method = "conservative")
print(globalsC)

## Will identify 'b'
globalsL <- globalsOf(expr, method = "liberal")
print(globalsL)

A representation of a set of globals

Description

A representation of a set of globals

Usage

Globals(object, ...)

Arguments

object

A named list.

...

Not used.

Value

An object of class Globals, which is a named list of the value of the globals, where the element names are the names of the globals. Attribute where is a named list of the same length and with the same names.

See Also

The globalsOf() function identifies globals from an R expression and returns a Globals object.


Locates and retrieves a set of global variables by their names

Description

Locates and retrieves a set of global variables by their names

Usage

globalsByName(names, envir = parent.frame(), mustExist = TRUE, ...)

Arguments

names

A character vector of global variable names.

envir

The environment from where to search for globals.

mustExist

If TRUE, an error is thrown if the object of the identified global cannot be located. Otherwise, the global is not returned.

...

Not used.

Value

A Globals object.


Identify the packages of the globals

Description

Identify the packages of the globals

Usage

## S3 method for class 'Globals'
packagesOf(globals, ...)

Arguments

globals

A Globals object.

...

Not used.

Value

Returns a character vector of package names.