How to access global instance variable from another instance in Ruby - ruby

Question

I'm new to Ruby and I'm trying to change some of my code to have OO design using our current framework. When converting my utility file to classes I encountered the following problem:
There are two functions *create_output_file* and *write_to* are framework methods (don't belong to any classes) that I cannot touch (They specifies where to write to the framework).
And there is a class A I wrote which needs to use the *write_to* to log the time and return status of the foo().
<!-- language: lang-rb -->
def create_output_file(params)
#output_file = params["SS_output_file"]
#hand = File.open(#output_file, "a")
write_to "New Run - Shell Cmd\n\n"
return true
end
def write_to(message, newline = true)
return if message.nil?
sep = newline ? "\n" : ""
#hand.print(message + sep)
print(message + sep)
end
def this_is_dum
print("This is to show class A have access to global methods.\n")
end
class A
def foo()
# Do something that needs the status of instance A
this_is_dum()
write_to("This is the current status!")
end
end
# Main routine
params = {}
params["SS_output_file"] = "./debugging_log"
create_output_file(params) #sets the #hand file handle
A.new.foo
These are the outputs I'm getting:
New Run - Shell Cmd:
This is to show class A have access to global methods.
D:/data/weshi/workspace/RubyBRPM2/scripts/Random.rb:12:in `write_to':
private method `print' called for nil:NilClass (NoMethodError)
from D:/data/weshi/workspace/RubyBRPM2/scripts/Random.rb:18:in
`foo' from
D:/data/weshi/workspace/RubyBRPM2/scripts/Random.rb:26:in
`'
After digging a bit I found that #hand was not accessed during the foo() scope.
I'm not sure how I'll be able to access the #hand variable inside class A and what it means without assigning to a class. But I do need the write_to function to work in accordance to the whole framework. Any suggestions or instructions are welcomed and appreciated.

Answer 1

You can give #hand to your A instance in the constructor like that:
def create_output_file(params)
#output_file = params["SS_output_file"]
#hand = File.open(#output_file, "a")
write_to "New Run - Shell Cmd\n\n"
return true
end
def write_to(message, newline = true)
return if message.nil?
sep = newline ? "\n" : ""
#hand.print(message + sep)
print(message + sep)
end
def this_is_dum
print("This is to show class A have access to global methods.\n")
end
class A
def initialize(hand)
#hand = hand
end
def foo()
# Do something that needs the status of instance A
this_is_dum()
write_to("This is the current status!")
end
end
# Main routine
params = {}
params["SS_output_file"] = "./debugging_log"
create_output_file(params) #sets the #hand file handle
A.new(#hand).foo
The output is:
New Run - Shell Cmd
This is to show class A have access to global methods.
This is the current status!
Otherwise I found that which may be a little bit more complicated.