c_extensions/c_globals.rb

tests/_examples/c_extensions/c_globals.rb in the metorex repository.

# A C extension defining globals whose values live in C memory or come from
# C functions, and reading and writing Ruby's globals by name.
require "tmpdir"
require_relative "build_helper"

directory = Dir.mktmpdir
require(build_extension("c_globals.c", "c_globals", directory))
globals = CGlobals.new
globals.define_all

p($c_stored)
$c_stored = "written from Ruby"
p(globals.stored_now)
p($c_fixed)
report { eval("$c_fixed = 1") }
$c_doubled = 21
p($c_doubled)
p($c_defaults)
p($c_nowhere)
$c_nowhere = :ignored
p($c_nowhere)
p($c_virtual)
report { eval("$c_virtual = 1") }
p($c_counting)
p($c_counting)
$c_counting = 100
p($c_counting)
traced = []
trace_var(:$c_doubled) { |value| traced << value }
$c_doubled = 4
untrace_var(:$c_doubled)
p([traced, $c_doubled])

p([globals.get("$c_doubled"), globals.get("c_doubled")])
p(globals.set("$from_c", :set))
p($from_c)
p(globals.get("from_c"))
p(globals.names.include?(:$c_counting))
p(globals.last_line("the last line"))
p($_)
p(globals.separators)
$; = ","
$, = "-"
$\ = "!"
p(globals.separators)
$; = nil
$, = nil
$\ = nil
p(globals.separators.last.frozen?)
p(globals.streams.map(&:fileno))

FileUtils.rm_rf(directory)

Output:

"stored in C"
"written from Ruby"
15
NameError: $c_fixed is a read-only variable
42
"written from Ruby"
nil
nil
false
NameError: $c_virtual is a read-only variable
[:$c_counting, 0]
[:$c_counting, 1]
[:$c_counting, 100]
[[4], 8]
[8, 8]
:set
:set
:set
true
"the last line"
"the last line"
[nil, "\n", nil, nil, "\n"]
[",", "\n", "-", "!", "\n"]
true
[0, 1, 2, 1]