I have a fairly open-ended question about the handling of package dependencies that is inspired by the precise distinction between "Depends", "Imports", and "Suggests" listed in DESCRIPTION.
Some background, as I understand it: Prior to requiring package namespaces, we listed package dependencies in "Depends" because the required package had to be (1) installed and (2) on the search path in order to access its functions. After introducing and requiring namespaces, there are very few circumstances in which "Depends" is needed because functions from the required package can either be imported (via "Imports" and NAMESPACE) and/or referred to using the `pkg::fun()` style. "Suggests" packages are maybe needed for examples, vignettes, etc. but are not installed by default via `install.packages()`, so are not guaranteed to be available. Some observations: 1. "Depends" seems to be less useful than before, except in rare cases where a package needs to be (a) installed, (b) loaded, and (c) on the search path. Imports covers most package dependency use cases. 2. There is a gap in functionality between "Imports" and "Suggests". Sometimes there is a need for functions that should be available (i.e., installed) but do not need to be loaded or imported because they are rarely used (e.g., graphing functions). Importing the functions adds bloat but only putting their package in "Suggests" does not guarantee availability when, for example, calling `requireNamespace()` or `require()`. Suggestion: Might it be useful to have a category between "Imports" and "Suggests" that covers packages that should be installed but not imported? This could be done by changing `install.packages()` to cover "Suggests" by default, changing the meaning of "Depends" and "Imports", or adding a new category to DESCRIPTION. I am interested in hearing your thoughts on this issue. Best, -Thomas Thomas J. Leeper http://www.thomasleeper.com ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
