getNested: Get Nested (generic)

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

Description

Retrieves value from a nested object structure based on a path-like id with the last ID component being the actual object name that contains the value.

Usage

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getNested(id, where = parent.frame(), default = NULL, strict = c(0, 1, 2),
  ...)

Arguments

id

Signature argument. Object containing path-like name/ID information.

where

Signature argument. Object containing location information.

default

ANY. Value to be returned if component does not exist.

strict

logical. Controls what happens when id points to a non-existing component:

  • 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.

Path-like identifiers

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. a$b$c$...$z and a$b$c$...$z <- value). Of course, "atomic" paths (e.g. only a) are also valid.

Author(s)

Janko Thyson [email protected]

References

http://github.com/Rappster/nestr

See Also

getNested-char-env-method, setNested, rmNested

Examples

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## Not run: 

## Also see examples at `?setNested`
  
##------------------------------------------------------------------------------
## Basics //
##------------------------------------------------------------------------------

setNested(id = "test", value = TRUE)
getNested(id = "test")
## --> leaf

setNested(id = "a/b/c", value = 10, gap = TRUE)
ls(getNested(id = "a"))
## --> branch
ls(getNested(id = "a/b"))
## --> branch
getNested(id = "a/b/c")
## --> leaf
  
## Clean up //
rm(test)
rm(a)

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

where <- new.env()
setNested(id = "a/b/c", value = 10, where = where, gap = TRUE)
getNested(id = "a/b/c", where = where)

## Clean up //
rm(where)

##------------------------------------------------------------------------------
## Different `default` //
##------------------------------------------------------------------------------

setNested(id = "test", value = 10)
getNested(id = "test", default = NA)
getNested(id = "z", default = NA)
getNested(id = "z/a/b", default = NA)

getNested(id = "test", default = "nope")
getNested(id = "z", default = "nope")
getNested(id = "z/a/b", default = "nope")

## Clean up //
rm(test)


## End(Not run)

rappster/nestr documentation built on May 24, 2017, 7:33 p.m.