env_names: Names and numbers of symbols bound in an environment

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Names and numbers of symbols bound in an environment

Description

env_names() returns object names from an enviroment env as a character vector. All names are returned, even those starting with a dot. env_length() returns the number of bindings.

Usage

env_names(env)

env_length(env)

Arguments

env	An environment.

Value

A character vector of object names.

Names of symbols and objects

Technically, objects are bound to symbols rather than strings, since the R interpreter evaluates symbols (see is_expression() for a discussion of symbolic objects versus literal objects). However it is often more convenient to work with strings. In rlang terminology, the string corresponding to a symbol is called the name of the symbol (or by extension the name of an object bound to a symbol).

Encoding

There are deep encoding issues when you convert a string to symbol and vice versa. Symbols are always in the native encoding. If that encoding (let's say latin1) cannot support some characters, these characters are serialised to ASCII. That's why you sometimes see strings looking like ⁠<U+1234>⁠, especially if you're running Windows (as R doesn't support UTF-8 as native encoding on that platform).

To alleviate some of the encoding pain, env_names() always returns a UTF-8 character vector (which is fine even on Windows) with ASCII unicode points translated back to UTF-8.

Examples

env <- env(a = 1, b = 2)
env_names(env)

hadley/rlang documentation built on Nov. 1, 2024, 4 p.m.