Redis, Lua and global functions Redis 2.8.3 redis-rb 3.0.6

redis_lua_eval.rb

require 'redis'

redis = Redis.new
redis.script(:flush)
redis.flushdb

hello_name_lua_script = <<-HELLO_NAME_LUA_SCRIPT
local function hello_name(name)
  return("Hello " .. name)
end
rawset(_G, "hello_name", hello_name)
HELLO_NAME_LUA_SCRIPT

hello_name_sha = redis.eval(hello_name_lua_script)

use_hello_name_lua_script = <<-USE_HELLO_NAME_LUA_SCRIPT
return hello_name("David")
USE_HELLO_NAME_LUA_SCRIPT

use_hello_name_sha = redis.script(:load, use_hello_name_lua_script)
redis.evalsha(use_hello_name_sha)

redis_lua_eval_run.txt

1.9.3p484 :001 > require 'redis'
 => true
1.9.3p484 :002 >
1.9.3p484 :003 >   redis = Redis.new
 => #<Redis client v3.0.6 for redis://127.0.0.1:6379/0>
1.9.3p484 :004 > redis.script(:flush)
 => "OK"
1.9.3p484 :005 > redis.flushdb
 => "OK"
1.9.3p484 :006 >
1.9.3p484 :007 >   hello_name_lua_script = <<-HELLO_NAME_LUA_SCRIPT
1.9.3p484 :008"> local function hello_name(name)
1.9.3p484 :009">   return("Hello " .. name)
1.9.3p484 :010"> end
1.9.3p484 :011"> rawset(_G, "hello_name", hello_name)
1.9.3p484 :012"> HELLO_NAME_LUA_SCRIPT
 => "local function hello_name(name)\n  return(\"Hello \" .. name)\nend\nrawset(_G, \"hello_name\", hello_name)\n"
1.9.3p484 :013 >
1.9.3p484 :014 >   hello_name_sha = redis.eval(hello_name_lua_script)
 => nil
1.9.3p484 :015 >
1.9.3p484 :016 >   use_hello_name_lua_script = <<-USE_HELLO_NAME_LUA_SCRIPT
1.9.3p484 :017"> return hello_name("David")
1.9.3p484 :018"> USE_HELLO_NAME_LUA_SCRIPT
 => "return hello_name(\"David\")\n"
1.9.3p484 :019 >
1.9.3p484 :020 >   use_hello_name_sha = redis.script(:load, use_hello_name_lua_script)
 => "4f7f594b261bc8cec50a6ef445ef43ca156f0bd2"
1.9.3p484 :021 > redis.evalsha(use_hello_name_sha)
 => "Hello David"
1.9.3p484 :022 >

redis_lua_script_load.rb

require 'redis'

redis = Redis.new
redis.script(:flush)
redis.flushdb

hello_name_lua_script = <<-HELLO_NAME_LUA_SCRIPT
local function hello_name(name)
  return("Hello " .. name)
end
rawset(_G, "hello_name", hello_name)
HELLO_NAME_LUA_SCRIPT

# Using script load here instead of eval
hello_name_sha = redis.script(:load, hello_name_lua_script)

use_hello_name_lua_script = <<-USE_HELLO_NAME_LUA_SCRIPT
return hello_name("David")
USE_HELLO_NAME_LUA_SCRIPT

use_hello_name_sha = redis.script(:load, use_hello_name_lua_script)
redis.evalsha(use_hello_name_sha)

redis_lua_script_load_run.txt

1.9.3p484 :001 > require 'redis'
 => true
1.9.3p484 :002 >
1.9.3p484 :003 >   redis = Redis.new
 => #<Redis client v3.0.6 for redis://127.0.0.1:6379/0>
1.9.3p484 :004 > redis.script(:flush)
 => "OK"
1.9.3p484 :005 > redis.flushdb
 => "OK"
1.9.3p484 :006 >
1.9.3p484 :007 >   hello_name_lua_script = <<-HELLO_NAME_LUA_SCRIPT
1.9.3p484 :008"> local function hello_name(name)
1.9.3p484 :009">   return("Hello " .. name)
1.9.3p484 :010"> end
1.9.3p484 :011"> rawset(_G, "hello_name", hello_name)
1.9.3p484 :012"> HELLO_NAME_LUA_SCRIPT
 => "local function hello_name(name)\n  return(\"Hello \" .. name)\nend\nrawset(_G, \"hello_name\", hello_name)\n"
1.9.3p484 :013 >
1.9.3p484 :014 >   hello_name_sha = redis.script(:load, hello_name_lua_script)
 => "94babaed36833c7019d5fc0d9b8b2ecaf59a13e9"
1.9.3p484 :015 >
1.9.3p484 :016 >   use_hello_name_lua_script = <<-USE_HELLO_NAME_LUA_SCRIPT
1.9.3p484 :017"> return hello_name("David")
1.9.3p484 :018"> USE_HELLO_NAME_LUA_SCRIPT
 => "return hello_name(\"David\")\n"
1.9.3p484 :019 >
1.9.3p484 :020 >   use_hello_name_sha = redis.script(:load, use_hello_name_lua_script)
 => "4f7f594b261bc8cec50a6ef445ef43ca156f0bd2"
1.9.3p484 :021 > redis.evalsha(use_hello_name_sha)
Redis::CommandError: ERR Error running script (call to f_4f7f594b261bc8cec50a6ef445ef43ca156f0bd2): @enable_strict_lua:14: user_script:1: Script attempted to access unexisting global variable 'hello_name'
redis.evalsha(use_hello_name_sha)