I've used a gem and tried to create a method (trans) in my code.
require 'yandex-translator'
translator = Yandex::Translator.new(api_key)
def trans(text)
a = translator.translate text, to: "ru"
return a
end
puts trans("stack")
When I run the code, I get this error:
'trans': undefined local variable or method `translator' for main:Object (NameError)
Why did I get this error, and how can I solve this?
translator variable in this code is defined on class level, hence it’s a local variable in main context (since the whole code is executed in main context.)
You are trying to call it from the instance context, where it is obviously not defined. The easiest way to overcome it, would be to define #translator as being a class’ instance variable:
#translator = Yandex::Translator.new(api_key)
def trans(text)
#translator.translate text, to: "ru"
end
Because in this way you are looking for a local variable translator and you have not. Some solutions:
make translator global
$translator = Yandex::Translator.new(api_key)
or pass translator to trans method
def trans(translator, text)
translator.translate text, to: "ru"
end
Related
Almost all of you used URI module to convert a url string to an object in order to make some validation or change.
Example:
require 'uri'
URI('https://google.com')
# => #<URI::HTTPS https://google.com>
As you can see, the result is the HTTPS object under the URI module.
So, there is a question what is run when you write module/class name with round braces like the line of code above.
I thought, it is implicit calling of call method, but I got NoMethodError.
Example:
class MyClass
def self.call
puts 'You were right!'
end
end
MyClass()
# => NoMethodError: undefined method `MyClass' for main:Object
Funny enough, with the code you've shown, MyClass.() works (which is an alias for .call).
However in the case of URI, this actually a method (methods can begin with capitals). You can see the source code here: https://apidock.com/ruby/Kernel/URI/instance
I did the 'requir_relative' but still got the NoMethodError.
There are 2 ruby files, under 'run.rb' I have this
class Run
def separate(data)
hash_block = []
(0...data.count).each do |i|
f = data[i].split('|')
hash_block[i] = Hashing.new(f[0].to_i, f[1], f[2], f[3], f[4])
end
hash_block
end
end
and then in the main file, I did these:
require_relative 'run'
...some codes...
to_separate = IO.readlines(ARGV[0])
separated = separate(to_separate)
...some codes...
but I still get this:
in `block in <main>': undefined method `separate' for main:Object (NoMethodError)
If I cut the method and paste it in the main file it will work as expected but that is something I wanted to avoid.
In order to call the method within the class Run you have to instantiate it. Since is an instance method. The way your calling the class is giving you the error undefined because it can not find it with in the scope of your current file
run_instance = Run.new
to_separate = IO.readlines(ARGV[0])
sperated = run_instance.separate(to_separate)
You required the file, but in that file you have a class definition. separate is inside that class (and that's an instance method), so you need an object to call the method on.
separated = Run.new.separate(to_separate)
I'm trying to run this code"
FACTORY = %w(ProcessedTransaction Chargeback).freeze
FACTORY.constantize.each do |factory|
factory.public_send(:delete_all)
end
end
But I get this error: NoMethodError: undefined methodconstantize' for #`
Do you know how I can solve the issue?
In ruby uppercased variables are constants by default so you can't call constantize on it. In your case it's just an array so this should work:
FACTORY = %w(ProcessedTransaction Chargeback).freeze
FACTORY.each do |factory|
factory.constantize.public_send(:delete_all)
end
You can call String#constantize only on strings but you are calling it on array FACTORY.
Remove FACTORY.constantize and add factory.constantize.public_send(:delete_all)
Also make sure you have ActiveSupport::Inflector required
I'm playing with some meta-programming concepts and wonder if something I want to do is simply possible.
There's simple DLS for events,
//test_events.rb
event 'monthly events are suspiciously high' do
true
end
and the script should shout out when event returns true, I try to do this without polluting global namespace with method event, and any instance variables. So I try something like this:
Dir.glob('*_events.rb').each do |file|
MyClass = Class.new do
define_method :event do |name, &block|
#events[name] = block
end
end
env = MyClass.new
env.instance_eval{#events = {}}
env.instance_eval{load(file)}
end
So for each *_events.rb file I would like to load it in context of MyClass (i know that with 2nd loop of Dir.glob#each it will complain about already defined const - not important now).
The problem is with env.instance_eval{load(file)} code in test_events.rb is run in Object context, because I get
undefined method `event' for main:Object (NoMethodError)
Is there a way to do it? ( I try now in 1.9.3 but changing version up is not a problem since it's just exercise)
instance_eval can take a String as its argument instead of a block, so rather than load (which as you suggest will load the file in the top level) you need to read the file contents into a string to pass in, something like:
env.instance_eval(File.read(file))
RuNubie here. I've got a class Login that logs into gmail using the net/IMAP library. What is happening is that I create a new instance of that class, such as:
a = Login.new("username", "gmail.com", "passw")
Then, I'm working on other classes that will do some "stuff" with the mailbox. The problem is that the #imap variable I've defined in Login seems to have disappeared (due to scoping I assume).
This is how #imap is declared in Login class:
#imap = Net::IMAP.new('imap.gmail.com',993,true,nil,false)
So this:
#today = Date.today
#received_today = imap.search(["SINCE", #today.strftime("%d-%b-%Y")]).count.to_s
...returns an error. These are the two errors I've gotten while playing around with this. The first one is when I use imap, the second one is when I try #imap:
NameError: undefined local variable or method `imap' for #<Object:0x10718d2a8>
NoMethodError: undefined method `search' for nil:NilClass
What are the best practices for dealing with a situation like this? Is the only solution to define my methods that do "stuff" in the same class where I'm creating the new instance of Net::IMAP? Is declaring #imap as a global variable $imap a bad practice? So confused, I bet the answer is very simple and obvious too, but I'm just not seeing it. Thanks!
This:
#received_today = imap.search(["SINCE", #today.strftime("%d-%b-%Y")]).count.to_s
won't work because, well, there is no imap in scope at that point and so you get a NameError. When you try it like this:
#received_today = #imap.search(["SINCE", #today.strftime("%d-%b-%Y")]).count.to_s
You get a NoMethodError because instance variables, such as #imap, are automatically created at first use and initialized as nil. Your real #imap is in another object so you can't refer to it as #imap anywhere else.
I think you want a structure more like this:
class User
def imap
if(!#imap)
#imap = Net::IMAP.new('imap.gmail.com', 993, true, nil, false)
# and presumably an #imap.authenticate too...
end
#imap
end
end
class OtherOne
def some_method(user)
#today = Date.today
#received_today = user.imap.search(["SINCE", #today.strftime("%d-%b-%Y")]).count.to_s
end
end
Keep your Net::IMAP localized inside your User and let other objects use it by providing a simple accessor method.
Oh and that global $imap idea, I'll just pretend I didn't see that as globals are almost always a really bad idea.
a shorter way to define the imap variable in the User class, which is pretty much the same as what mu posted:
class User
def imap
#imap ||= Net::IMAP.new...
end
end