Using string variable to call a method

Ruby
1

Hello all,

How can I use a string variable as part of a method name I’m calling?
For
example say I want to call the method say_hello using the following:

def say_hello
puts “Hello!”
end

str = “hello”

say_???

Thanks in advance!! – BTR

2

Alle lunedì 7 gennaio 2008, Bryan R. ha scritto:

say_???

Thanks in advance!! – BTR

send “say_#{str}”

Stefano

3

You can use: eval, instance_eval, class_eval, module_eval oder send
The different evals are described here:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/192513
(click on the “N” to read the next message in the thread)
send is as far as I understand it, used to send messages to objects.
Keep in mind that method calls are messages send to objects.

4

In general, the send method is preferred over evalling a string when
possible.

In addition to send “say_#{str}”, you can do method(“say_#{str}”.to_sym)
.call.

Dan

5

Along these same lines, is it possible to do a require and include
dynamically, getting the name of the file to require and module to
include
from a string?

6

send :include, Module.const_get(ARGV[1]) worked. Thanks!!

7

require is obvious, the method takes a string already.

Including a module, I think you can do:

ClassName.send(:include, Module.const_get(“ModuleName”))

or if you’re working with an instance variable, replace :include with
:extend.

Jason