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reexport

miniextendr_api::prelude

Macro reexport 

Source 
reexport!() { /* proc-macro */ }
Expand description

Re-export other packages’ R functions from this package.

Each item names a package and one of its exports. The generated R wrappers get roxygen2’s re-export block for it, so devtools::document() writes importFrom(pkg, name) and export(name) to NAMESPACE and lists name on man/reexports.Rd:

#' @importFrom generics tidy
#' @export
generics::tidy

The usual reason is a generic the package registers S3 methods for, such as generics::tidy() for #[miniextendr(s3(generic = "tidy", class = "my_fit"))]: with only the package attached, a bare tidy(fit) then finds the generic and dispatches to the method.

ⓘ
use miniextendr_api::reexport;

reexport!(generics::tidy, generics::glance, generics::augment);
reexport!(data.table::fread, stats::na.omit, magrittr::"%>%");
  • The package and the name are identifiers joined by .. A name that is not a syntactic R name is a string literal (magrittr::"%>%"); the R code backticks it.
  • The package has to be in the Imports field of DESCRIPTION, which the importFrom() needs; R CMD check reports a missing one.
  • Any number of invocations may name the same pkg::name, so each module can re-export the generics its methods are for; the wrappers get one block per pkg::name.
  • The wrapper writer refuses, at install time, a name re-exported from two packages, and a name the package’s generated wrappers also define or export (an S3 generic of an impl block, a function, an @rawNamespace export(...)). Hand-written R files are not checked.
  • A package name that is not an R package name, a name that is not an R name, and two packages for one name in one invocation are compile errors, all reported at once.