The Problem with {foreach} Package in R Packages

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In this answer, we will discuss a common mistake when working with packages in R development.

Step 1: The Error Message

The error message indicates that there is no function called library from the namespace of the {foreach} package. This is true because you should not load packages by using the library() function in a package.

Step 2: Loading Packages in R Packages

To load functions from other packages, use either the import or importFrom syntax.

Example

# Bad practice
library(foreach)

Correct Practice

# Good practice
import(foreach::library)

Step 3: Removing Unnecessary Lines

In your NAMESPACE file, you have two lines related to the {foreach} package:

# import(foreach::library)

importFrom(foreach, "%dopar%")
importFrom(foreach, foreach)

The line that loads the library function from the {foreach} package is not necessary and can be removed.

Step 4: Conclusion

When working with R packages, it’s essential to understand how to correctly load functions from other packages. The correct syntax for loading a specific function is to use either import or importFrom. Also, make sure to remove any unnecessary lines related to package loading.

Last modified on 2023-11-22