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72 lines
2.6 KiB
Plaintext
72 lines
2.6 KiB
Plaintext
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% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/hello.R
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\name{import}
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\alias{import}
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\title{Import a module into the current scope}
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\usage{
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import(module, attach, attach_operators = TRUE)
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}
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\arguments{
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\item{module}{an identifier specifying the full module path}
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\item{attach}{if \code{TRUE}, attach the newly loaded module to the object
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search path (see \code{Details})}
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\item{attach_operators}{if \code{TRUE}, attach operators of module to the
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object search path, even if \code{attach} is \code{FALSE}}
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}
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\value{
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the loaded module environment (invisible)
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}
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\description{
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\code{module = import('module')} imports a specified module and makes its
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code available via the environment-like object it returns.
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}
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\details{
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Modules are loaded in an isolated environment which is returned, and
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optionally attached to the object search path of the current scope (if
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argument \code{attach} is \code{TRUE}).
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\code{attach} defaults to \code{FALSE}. However, in interactive code it is
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often helpful to attach packages by default. Therefore, in interactive code
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invoked directly from the terminal only (i.e. not within modules),
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\code{attach} defaults to the value of \code{options('import.attach')}, which
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can be set to \code{TRUE} or \code{FALSE} depending on the user’s preference.
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\code{attach_operators} causes \emph{operators} to be attached by default,
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because operators can only be invoked in R if they re found in the search
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path. Not attaching them therefore drastically limits a module’s usefulness.
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Modules are searched in the module search path \code{options('import.path')}.
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This is a vector of paths to consider, from the highest to the lowest
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priority. The current directory is \emph{always} considered first. That is,
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if a file \code{a.r} exists both in the current directory and in a module
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search path, the local file \code{./a.r} will be loaded.
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Module names can be fully qualified to refer to nested paths. See
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\code{Examples}.
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}
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\note{
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Unlike for packages, attaching happens \emph{locally}: if
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\code{import} is executed in the global environment, the effect is the same.
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Otherwise, the imported module is inserted as the parent of the current
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\code{environment()}. When used (globally) \emph{inside} a module, the newly
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imported module is only available inside the module’s search path, not
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outside it (nor in other modules which might be loaded).
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}
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\examples{
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# `a.r` is a file in the local directory containing a function `f`.
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a = import('a')
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a$f()
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# b/c.r is a file in path `b`, containing a function `g`.
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import('b/c', attach = TRUE)
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g() # No module name qualification necessary
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}
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\seealso{
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\code{unload}
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\code{reload}
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\code{module_name}
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}
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