litedown (version 0.7)

reactor: Get and set chunk options

Description

Chunk options are stored in an environment returned by reactor(). Option values can be queried by passing their names to reactor(), and set by passing named values.

Usage

reactor(...)

Value

With no arguments, reactor() returns an environment that stores the options, which can also be used to get or set options. For example, with opts = reactor(), opts$name returns an option value, and opts$name = value sets an option to a value.

With named arguments, reactor() sets options and returns a list of their old values (e.g., reactor(echo = FALSE, fig.width = 8)). The returned list can be passed to reactor() later to restore the options.

With unnamed arguments, reactor() returns option values after received option names as input. If one name is received, its value is returned (e.g., reactor('echo')). If multiple names are received, a named list of values is returned (e.g., reactor(c('echo', 'fig.width'))). A special case is that if only one unnamed argument is received and it takes a list of named values, the list will be used to set options, e.g., reactor(list(echo = FALSE, fig.width = 8)), which is equivalent to reactor(echo = FALSE, fig.width = 8).

Arguments

...

Named values (for setting) or unnamed values (for getting).

Examples

# get options
litedown::reactor("echo")
litedown::reactor(c("echo", "fig.width"))

# set options
old = litedown::reactor(echo = FALSE, fig.width = 8)
litedown::reactor(c("echo", "fig.width"))
litedown::reactor(old)  # restore options

# use the environment directly
opts = litedown::reactor()
opts$echo
mget(c("echo", "fig.width"), opts)
ls(opts)  # built-in options