storage.has {memofunc}

Has key has been used to store a value?

Description

Indicates if a given key has a associated value stored in the storage or not.

Usage

storage.has(storage, key)

Arguments

storage

initialized storage

key

key to check for stored value

Value

TRUE if key has an associated stored value, FALSE otherwise.

Examples

library(magrittr)

# initialize default memory storage
my.storage <- storage.init()

# set a value into storage
storage.set(my.storage, "name", "Roy Wetherall")

# .. and some more
my.storage %>% 
  storage.set("age", 45) %>% 
  storage.set("alive", TRUE) %>%
  storage.set("children", c("Peter", "Grace", "Lucy"))

# check a key has been set
if (storage.has(my.storage, "name")) print("I know your name!")

# .. and that a key hasn't been set
if (!storage.has(my.storage, "address")) print("I don't know where you live!")

# get some values from storage
sprintf(
  "%s is %i years old.", 
  storage.get(my.storage, "name"),
  storage.get(my.storage, "age"))

# remove a value from storage
storage.unset(my.storage, "children")

# .. and show it's not there anymore
if (!storage.has(my.storage, "address")) print("I don't know who your children are!")

# clear all values from storage
storage.clear(my.storage)

# .. and everything is gone
if (!storage.has(my.storage, "name") && !storage.has(my.storage, "age")) print("I know nothing!")