package options

Description Usage Arguments Path-like identifiers Author(s) References See Also Examples

Checks if a meta object exists inside of the respective environment for such information within an option container based on a path-like id with the last ID component being the actual object name that the function looks for. See getOptionContainer.

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existsMetaValue(id, where = tryCatch(devtools::as.package(".")$package, error
  = function(cond) {     stop("Invalid default value for `where`") }),
  sub_id = character(), default = NULL, strict = c(0, 1, 2), ...)

`id`	Signature argument. Object containing path-like name/ID information.
`where`	Signature argument. Object containing information about the location of the option container that is to be used. Typically, this either corresponds to the name/ID of a package/package project or an instance of a custom class for which suitable methods in the context of managing options are defined (see other methods of this package that have signature arguments `id` or `where`).
`sub_id`	`character`. Optional ID for a sub layer. Useful for a hub-like option container structure.
`default`	`ANY`. Value to be returned if option does not exist. See `getOption` and `getNested`.
`strict`	`logical`. Controls what happens when `id` points to a non-existing meta object: 0: ignore and return `FALSE` to signal that the assignment process was not successful or `fail_value` depending on the value of `return_status` 1: ignore and with warning and return `FALSE` 2: ignore and with error
`...`	Further arguments to be passed to subsequent functions/methods.

Values for id are expected to be of structure a/b/c/.../z, i.e. path-like identifiers using a slash as separator. The identifier is transformed to a$b$c$...$z and then in turn to a valid get or assign expression (i.e. something similar to getOptionContainer(...)$a$b$c$...$z and getOptionContainer(...)$a$b$c$...$z <- value). Of course, "atomic" paths (e.g. only a) are also valid.

Janko Thyson janko.thyson@gmail.com

http://github.com/Rappster/optionr

existsMetaValue-char-char-method, setMetaValue, getMetaValue, rmMetaValue

## Not run: 

##------------------------------------------------------------------------------
## Basics //
##------------------------------------------------------------------------------

setMetaValue(id = "test", value = TRUE)
existsMetaValue(id = "test")

setMetaValue(id = "a/b/c", value = 10)
existsMetaValue(id = "a")
existsMetaValue(id = "a/b")
existsMetaValue(id = "a/b/c")
existsMetaValue(id = "a/b/c/d")

existsMetaValue(id = "c")
existsMetaValue(id = "c/d/e")
  
##------------------------------------------------------------------------------
## Strictness levels //
##------------------------------------------------------------------------------

## Empty ID //
existsMetaValue(id = character())
try(existsMetaValue(id = character(), strict = 1))
try(existsMetaValue(id = character(), strict = 2))

## Not-existing //  
existsMetaValue(id = "c/d/e")
try(existsMetaValue(id = "c/d/e", strict = 1))
try(existsMetaValue(id = "c/d/e", strict = 2))

##------------------------------------------------------------------------------
## Explicit `where` //
##------------------------------------------------------------------------------

where <- new.env()
setMetaValue(id = "a/b/c", value = 10, where = where)
existsMetaValue(id = "a/b/c", where = where)
existsMetaValue(id = "a/b/c/d", where = where)
existsMetaValue(id = "c/d/e", where = where)

##------------------------------------------------------------------------------
## Sub ID //
##------------------------------------------------------------------------------

where <- new.env()
setMetaValue(id = "a/b/c", value = 10, where = where, sub_id = "sub")
ls(where)
existsMetaValue(id = "a/b/c", where = where, sub_id = "sub")
existsMetaValue(id = "a/b/c/d", where = where, sub_id = "sub")
existsMetaValue(id = "c/d/e", where = where, sub_id = "sub")


## End(Not run)