CODEWITHSUNDEEP
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R Yoda
R Yoda

Reputation: 8760

Load library into existing environment (equivalent to "local" parameter of "source")?

I am sourcing util functions in production into an environment to encapsulate (and group) the helper functions:

Helper file:

# File: Helper.R
hello <- function() {
  print("Hello world")
}

Client:

helper <- new.env()
source("Helper.R", local=helper)
helper$hello()   # call the helper function

How can I migrate my sourced "Helper.R" into a library without breaking the calls of the sourced functions?

What I want is something like

helper <- new.env()
library(Helper, local=helper)
helper$hello()   # call the helper function (loaded from the library now)

Is there a way to do this?

Upvotes: 3

Views: 1393

Answers (4)

Konrad Rudolph
Konrad Rudolph

Reputation: 545618

You can use the box::use() function in the ‘box’ package.

Then the following attaches a package locally:

box::use(pkg[...])

Alternatively, and potentially closer to what you actually want to do, you could use the following simpler code:

box::use(pkg)

Now the package is not attached at all, and its exported objects can be accessed via pkg$obj. This is somewhat similar to base R’s loadNamespace function, but does considerably more behind the scenes.

Finally, consider not putting your helper code into a package at all, but rather distributing it as a module. This is after all what the ‘box’ package was designed for: instead of creating a package, just distribute your helper.r code file (or folder) and then use it as follows:

box::use(./helper)

See the package website and vignette for a detailed description.

Upvotes: 1

R Yoda
R Yoda

Reputation: 8760

Another way could be:

# getNamespace returns the environment representing the name space name. The namespace is loaded if necessary.
# Internal function to support reflection on namespace objects!
env <- getNamespace("data.table")
cars <- env$as.data.table(mtcars)

This examples makes all objects of the package data.table available via the environment variable env.

Note: It uses an internal R function (I have no idea how big the risk of changes of this internal function really is).

Upvotes: 0

Sebastian
Sebastian

Reputation: 850

Adding to the list of suggestions you can also consider to use the modules package on CRAN (note I am the author). When you have your Helper.R file with:

hello <- function() {
  print("Hello world")
}

you can use

helper <- modules::use("Helper.R")
helper$hello()

to encapsulate your helper functions in their own environment. The package also provides some functions to manipulate the local namespace of a module (imports/exports).

Upvotes: 1

R Yoda
R Yoda

Reputation: 8760

I have found another package called import (similar to "modules") that allows importing packages into an environment:

https://github.com/smbache/import

This package is also on CRAN:

install.packages("import")

It allows importing selected, all exported ("public") or all (even not exported) functions of a package.

Example:

import::from(dplyr, arrange, .into = "datatools")

The import::from function is a convenient wrapper around getExportedValue.

Upvotes: 0

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