You may use the different accessors to communicate your intent to someone reading your code, and make it easier to write classes which will work correctly no matter how their public API is called. class Person attr_accessor :age … end Here, I can see that I may both read and write the age. class Person … Read more
You’ve got a workable idea, but the #flatten! is in the wrong place — it flattens its receiver, so you could use it to turn [1, 2, [‘foo’, ‘bar’]] into [1,2,’foo’,’bar’]. I’m doubtless forgetting some approaches, but you can concatenate: a1.concat a2 a1 + a2 # creates a new array, as does a1 += a2 … Read more
kind_of? and is_a? are synonymous. instance_of? is different from the other two in that it only returns true if the object is an instance of that exact class, not a subclass. Example: “hello”.is_a? Object and “hello”.kind_of? Object return true because “hello” is a String and String is a subclass of Object. However “hello”.instance_of? Object returns … Read more
I’m going to heavily quote the Object documentation here, because I think it has some great explanations. I encourage you to read it, and also the documentation for these methods as they’re overridden in other classes, like String. Side note: if you want to try these out for yourself on different objects, use something like … Read more
Use the defined? keyword (documentation). It will return a String with the kind of the item, or nil if it doesn’t exist. >> a = 1 => 1 >> defined? a => “local-variable” >> defined? b => nil >> defined? nil => “nil” >> defined? String => “constant” >> defined? 1 => “expression” As skalee … Read more
For ruby >= 2.4 you can use sum: array.sum For ruby < 2.4 you can use inject: array.inject(0, :+) Note: the 0 base case is needed otherwise nil will be returned on empty arrays: > [].inject(:+) nil > [].inject(0, :+) 0
There’s a simple command built-in that will pull it: rvm implode This will remove the rvm/ directory and all the rubies built within it. In order to remove the final trace of rvm, you need to remove the rvm gem, too, if you installed that: gem uninstall rvm There may be elements left over from … Read more
Try adding –user-install instead of using sudo: gem install mygem –user-install
Just use Array#sample: [:foo, :bar].sample # => :foo, or :bar 🙂 It is available in Ruby 1.9.1+. To be also able to use it with an earlier version of Ruby, you could require “backports/1.9.1/array/sample”. Note that in Ruby 1.8.7 it exists under the unfortunate name choice; it was renamed in later version so you shouldn’t … Read more
In general, methods that end in ! indicate that the method will modify the object it’s called on. Ruby calls these as “dangerous methods” because they change state that someone else might have a reference to. Here’s a simple example for strings: foo = “A STRING” # a string called foo foo.downcase! # modifies foo … Read more