dictionary {rlang} | R Documentation |
Dictionaries are a concept of types modelled after R environments. Dictionaries are containers of R objects that:
Contain uniquely named objects.
Can only be indexed by name. They must implement the extracting
operators $
and [[
. The latter returns an error when indexed
by position because dictionaries are not vectors (they are
unordered).
Report a clear error message when asked to extract a name that
does not exist. This error message can be customised with the
lookup_msg
constructor argument.
as_dictionary(x, lookup_msg = NULL, read_only = FALSE) is_dictionary(x)
x |
An object for which you want to find associated data. |
lookup_msg |
An error message when your data source is accessed inappropriately (by position rather than name). |
read_only |
Whether users can replace elements of the dictionary. |
Dictionaries are used within the tidy evaluation framework for
creating pronouns that can be explicitly referred to from captured
code. See eval_tidy()
.