Fetch a resource relative to a director object.

Resources are R scripts that optionally have a "parser" attached which takes the result of executing the file, including all of its local variables, and does some additional computation. This is useful if, for example, you are trying to define a standard format for creating a reference class object by specifying some inputs, but want to make it easy to provide those inputs by users.

resource(name, ..., defining_environment. = parent.frame())

Arguments

name	character. The name of the resource (i.e. R script) relative to the root of the director object.
provides	list or environment. A list or environment of values to provide to the resource. The default is nothing, i.e., list(). Note that provides will be coerced to an environment, and its parent environment will be set to parent.env(topenv()) to prevent access to global variables (and encourage modularity and lack of side effects. There should always be a way to write your code without them).
body	logical. Whether or not to fetch the body of the resource.
soft	logical. Whether or not to modify the cache to reflect the resource modification time and other details.
tracking	logical. Whether or not to perform modification tracking by pushing accessed resources to the director's stack.
helper	logical. If TRUE, allow processing of helper files. If a file shares its name with the parent directory (e.g., "foo" and "foo/foo.R"), it is called an idempotent resource. Any other files in the same directory as the idempotence resource, besides the file itself, are called helper files, and are usually invisible to the director object (e.g., "foo/other.R" if "foo/foo.R" exists). If helper = TRUE, these will temporarily be treated as a resource so that we can track whether they were modified and re-use other directorResource features. By default, helper = FALSE.

Value

A directorResource object.

Details

This method will return a directorResource object that represents that particular R script. A resource can have a preprocessor and a link[=register_parser]{parser} attached to it.

The former determines how to source the R file. For example, if you need to inject additional variables prior to sourcing it, you can do so from the preprocessor.

The parser determines what to do with the R file after sourcing it. It can tell what the dependencies of the file are (i.e., what other resources were used when sourcing it), and whether or not it was modified (i.e., whether the R file or any of its dependencies were modified).

Together, a preprocessor, parser, and source file compose a resource.