library("R.utils")

local <- Options()
print(local)
str(local)
print(names(local))
print(nbrOfOptions(local))
print(getLeaves(local))


# Query a missing option
cex <- getOption(local, "graphics/cex")
cat("graphics/cex =", cex, "\n")  # Returns NULL

# Query a missing option with default value
cex <- getOption(local, "graphics/cex", defaultValue=1)
cat("graphics/cex =", cex, "\n")  # Returns NULL

# Set option and get previous value
oldCex <- setOption(local, "graphics/cex", 2)
cat("previous graphics/cex =", oldCex, "\n")  # Returns NULL

# Set option again and get previous value
oldCex <- setOption(local, "graphics/cex", 3)
cat("previous graphics/cex =", oldCex, "\n")  # Returns 2

# Query a missing option with default value, which is ignored
cex <- getOption(local, "graphics/cex", defaultValue=1)
cat("graphics/cex =", cex, "\n")  # Returns 3

# Query multiple options with multiple default values
multi <- getOption(local, c("graphics/cex", "graphics/pch"), c(1,2))
print(multi)

# Check existance of multiple options
has <- hasOption(local, c("graphics/cex", "graphics/pch"))
print(has)

# Get a subtree of options
graphics <- getOption(local, "graphics")
print(graphics)

# Get the complete tree of options
all <- getOption(local)
print(all)