I want to use the object created in main script globally.
for ex I have different module in different file and class in different ruby file
FileNameModA.rb
module A
# ........
# some code here
# ........
end
FileNameModB.rb
module B
# ........
# some code here
# ........
objReport.addReport() # getting an error "ruby uninitialized local variable or object: Main"
end
FileNameClass_Report.rb
class Report
def addreport()
end
end
MainScript.rb
require "FileNameModA"
require "FileNameModB"
require "FileNameClass_Report"
include ModuleA
include ModuleB
objReport = Report.New
objReport.addReport() # Works fine here
Could you please let me know how to create and use object in different file/module of Ruby?
when you require "FileNameModB" it executes the definition of module B and that definition calls objReport.addReport which does not exist in that context
i'm not sure what are you trying to achieve by calling addReport during module definition but you could swap some lines and make it work like this:
require "FileNameClass_Report"
$objReport = Report.New
require "FileNameModA"
require "FileNameModB" # update your file to call $objReport.addReport
include ModuleA
include ModuleB
whole thing looks like a mess though, try to rethink your classes/modules to avoid including them into global object
Related
Rails 5.2 here.
I want to test a class defined in app/lib/legacy/export.rb:
# app/lib/legacy/export.rb
module Legacy
class Export
def initialize ; end
end
end
However, a test in test/services/legacy_export_test.rb
# test/services/legacy_export_test.rb
require 'test_helper'
class LegacyExportTest < ActiveSupport::TestCase
test 'can be initialized' do
Legacy::Export.new
end
end
will spit out NameError: uninitialized constant Legacy::Export.
It works well if I put the class definition in app/lib/export.rb (and remove the module definition).
I can also reference this class in Controllers and in the rails console (rails c).
Trying to reference the class starting with the top-level-"namespace" (::Legacy::Export) does not help either. I find answers to questions how to reference lib folders (and subdirectories) in the test/ folder, but this is not what I need.
require 'lib/legacy/export will tell me cannot load such file, as will require 'legacy/export'.
I assumed that the (Auto-)Load-stuff of Rails and MiniTest are the same, but obviously there is some additional configuration to be done.
What has to be done? Where would I find this information?
The problem is that your class namespace / class path doesn't match how Rails autoloading works out of the box.
When you use a class that wasn't previously declared, Rails by default will look on specific paths (defined on config.autoload_paths)
app/controllers
app/controllers/concerns
app/models
app/models/concerns
...
When you use User for the first time, as it's not defined (yet) it will loop over those paths and try to require app/controllers/user.rb, app/controllers/concerns/user.rb, app/models/user.rb, until it founds the User class
if your class is namespaced as Legacy::Export, then it will look for app/models/legacy/export.rb, app/models/concerns/legacy/export.rb, app/controllers/legacy/export.rb, etc.
That's why it can't find your class: Your file is located on app/lib, that's not within the paths Rails use to look for.
There are different solutions:
Option #1
Require the file explicitly. (The Ruby way)
require_relative '../../app/lib/legacy/export'
Option #2
Add app/lib to autoload_path (in config/application.rb)
(The Rails Way)
module YourApp
class Application < Rails::Application
# ...
config.autoload_paths << Rails.root.join("app/lib")
end
end
Option #3
Adapt namespace to match what autoloading expects (instead of changing the configuration)
Example: move you file to something like app/models/legacy/export.rb
I wrote a Ruby file my.rb, which has a module definition:
module MyModule
...
end
Another Ruby script requires my.rb on the fly, and I want to dynamically get the module name defined in my.rb. Is it possible?
You can use TracePoint to do that:
# :class is the start of a class or module definition
TracePoint.new(:class) do |trace|
puts "defined a class or module named: #{trace.self}"
end.enable do
require './my'
end
when running this script it will output:
defined a class or module named: MyModule
and only classes that get defined within the enable block get output
I'm pretty new to Ruby and facing a pretty basic problem i guess. I'm probably missing out on some basic concepts and constructs. So this is what i'm trying to do,
I'm writing a sinatra project, and i have a classes which are written in different files. The structure looks something of this sort,
project_name
- api.rb
- base.rb
- settings.rb
In my api.rb file i have defined a class and some methods, it also calls some methods form base.rb and base.rb calls some methods from settings.rb
In api.rb
require 'sinatra'
require 'json'
require 'uri'
require 'base' --> This is the base.rb which is resulting in error
module XX
class Api
def some_method
base = Base.new
base.setup
# some more code
end
end
end
In base.rb, it has the following code
require 'settings'
module XX
class Base
def setup
# some code
end
def some_method
#some code
end
end
end
When i just run ruby api.rb, i'm getting an error in the require statement, unable to load such file-- base (LoadError).
What is it that i'm missing here? Also, how is it that ruby know whether it a gem or a file required..does it check to see if the require is a file in the project and then goes on to check for a gem ? How is this process done in ruby?
Any help is much appreciated!
I have a module as following,
main.rb:
module Main
include Dad::Mam
end
and
in dad.rb:
module Dad
module Mam
puts "Mam is saying you are very lazy..."
end
end
How can I name this file? dad.rb is right?
but when running
$ ruby main.rb
I am getting an Error like,
main.rb:2:in <module:Main>': uninitialized constant Main::Dad
(NameError) from main.rb:1:in'
I need to show the sentance inside the puts under Mam module while running ruby main.rb,
I am confused about using ruby's modules, please anyone help me and guide me..
In this case, since you're just writing a simple script, use #require_relative
require_relative 'dad'
module Main
include Dad::Mam
end
For an actual app or library, you would want to manage the load path (a global variable holding an array that tells ruby where to look for files) and then use a normal require
I'm trying to use two Gems to access Amazon Web Services (AWS). One is the Amazon 'aws-sdk', the other is 'amazon-ec2'. I'm using the second as the aws-sdk does not cover the cloudwatch section of the amazon services.
The issue is that both load into the same namespace.
require 'aws-sdk' # aws-sdk gem
require 'AWS' # amazon-ec2 gem
config = {:access_key_id => 'abc', :secret_key => 'xyz'}
# start using the API with aws-sdk
ec2 = AWS::EC2.new(config)
# start using the API for anazon-ec2
cw = AWS::Cloudwatch::Base.new(config)
Now this understandably throws an error on the last line as the AWS module is pointing at the first required library, in this case aws-sdk.
NameError: uninitialized constant AWS::Cloudwatch
So, is it possible for me to load one of those into another namespace? Something like
require 'aws-sdk', 'AWS_SDK'
require 'AWS', 'AWS_EC2'
ec2 = AWS_SDK::EC2.new(config)
cw = AWS_EC2::Cloudwatch::Base.new(config)
Or is there another trick I could use here?
Thanks
In Ruby, modules with the same name from different gems don't replace each other. If one gem implements
module AWS
class Foo
end
end
and another implements
module AWS
class Bar
end
end
and you require them both, you will end up with an AWS module that contains both a class Foo and a class Bar (unless the second does something really tricky like explicitly undefining anything already present in the module, before defining its own stuff, which is very unlikely). As long as the second gem doesn't redefine any methods in the first gem (or attempts to use a module as a class or vice versa), they should both work fine. I think you may be looking for the wrong solution.
Edit:
And in fact, what happens for me (in an environment with only these gems present (aws-sdk 1.2.3 and amazon-ec2 0.9.17) and the exact code you listed above) is exactly that:
.rvm/gems/ree-1.8.7-2011.03#ec2/gems/amazon-ec2-0.9.17/lib/AWS/EC2.rb:2: EC2 is not a module (TypeError)
Could it be that an error gets swallowed somewhere and that the module AWS::Cloudwatch hasn't been defined, simply because the initialization of the gem goes awry?
I think I've found a solution that works, let me illustrate it with an example. Suppose we have to files a.rb and b.rb that define the same module with actual name clashes:
#file a.rb
module A
def self.greet
puts 'A'
end
end
#file b.rb
module A
def self.greet
puts 'other A'
end
end
If you need to require both of them, the following seems to do the trick:
require_relative 'a'
TMP_A = A.dup
A.greet # => A
TMP_A.greet # => A
require_relative 'b'
TMP_A2 = A
A.greet # => other A
TMP_A2.greet # => other A
TMP_A.greet # => A
Without the dup, TMP_A will also point to the A defined in b.rb after the require_relative, but the dup will ensure that a real copy is produced instead of simply holding a reference to the module.