General
Can I call
library/require/source inside a
module?
No, this usually won’t work: library (and
require) attaches names globally, rather than
inside the calling module. Inside a module, box::use must
be used instead.
Likewise, by default source evaluates the source code in
the global rather than in a local environment. This behaviour can be
changed by setting its local argument to a suitable
value.
Calling these functions inside a module will raise a warning which
can be silenced by setting
options(box.warn.legacy = FALSE). After changing this
option, ‘box’ needs to be (unloaded and) reloaded for the change to take
effect.
Can I use “meta packages” like ‘tidyverse’ with ‘box’?
No. You can use individual packages from the tidyverse via
box::use. But directly loading a “meta package” such as
‘tidverse’ is intentionally not supported.
“Meta packages” such as ‘tidyverse’ are antithetical to the purpose of ‘box’: the whole point of ‘box’ is to make package imports explicit, and to limit the number of names that are attached in the current scope. Using “meta packages” would undermine this and is therefore discouraged.
How to organise globally installed modules?
Module names need to be fully qualified, meaning that using them requires providing a name consisting of a prefix (at least one high-level namespace) and the module’s proper name. The choice of prefix is, to some extent, arbitrary. However, there are some common conventions that are worth following.
For example, it is common practice to use a company or user name
(look at code sharing websites such as GitHub for inspiration). A
project consisting of several nested modules might also serve the same
purpose. For example, if ‘dplyr’ were implemented as a module, its
common fully qualified name would probably be
tidyverse/dplyr.
As a concrete example, consider the following modules, stored in the module search path:
‹box.path›
├── klmr
│ ├── fun
│ ├── ggplots
│ └── sys
├── mschubert
│ └── ebits
└── …Using the sys module (more precisely,
klmr/sys) requires the following R code:
box::use(klmr/sys)Common error messages
“object ‘X’ not found” inside a module
Inside modules, only the ‘base’ package is attached. All other packages need to be attached, including all core R packages that are otherwise attached by default. This includes ‘stats’, ‘graphics’, ‘grDevices’, ‘utils’, ‘datasets’ and ‘methods’.
To use names from any of these packages, the packages need to be
loaded via box::use, same as third-party packages.
Alternatively, the standard module r/core can be used (and,
optionally, attached):
box::use(r/core[...])This is equivalent to using and attaching the default R packages ‘methods’, ‘stats’, ‘graphics’, ‘grDevices’ and ‘utils’, and is therefore similar to the state of a regular R session.
This module ships with ‘box’ and is always findable.
“there is no package called ‘X’” when running
box::use(X), even though the module ‘X’ exists
box::use(name) never attempts to load a module, it
always attempts to load a package called ‘name’, and fails if
no such package exists. Modules need to be either local and
start with . or .., or they need to be fully
qualified. This means that the full module name contains at least one
separator (/).
In practice, this means that modules inside the global module search
path (set via the environment variable R_BOX_PATH or via
getOption('box.path')), modules need to be located in
nested folders.
See how to organise globally installed modules? for details.