The proper way to determine the “type” of an object, which is a wobbly term in the Ruby world, is to call object.class. Since classes can inherit from other classes, if you want to determine if an object is “of a particular type” you might call object.is_a?(ClassName) to see if object is of type ClassName … Read more
Use the keyword next. If you do not want to continue to the next item, use break. When next is used within a block, it causes the block to exit immediately, returning control to the iterator method, which may then begin a new iteration by invoking the block again: f.each do |line| # Iterate over … Read more
Open your terminal and run curl -sSL https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer | bash -s stable When this is complete, you need to restart your terminal for the rvm command to work. Now, run rvm list known This shows the list of versions of the ruby. Now, run rvm install ruby@latest to get the latest ruby version. If you … Read more
There’s no difference, in fact map is implemented in C as rb_ary_collect and enum_collect (eg. there is a difference between map on an array and on any other enum, but no difference between map and collect). Why do both map and collect exist in Ruby? The map function has many naming conventions in different languages. … Read more
╔═══════════════╦═══════════════════════════╦═════════════════════════════════╗ ║ ║ class ║ module ║ ╠═══════════════╬═══════════════════════════╬═════════════════════════════════╣ ║ instantiation ║ can be instantiated ║ can *not* be instantiated ║ ╟───────────────╫───────────────────────────╫─────────────────────────────────╢ ║ usage ║ object creation ║ mixin facility. provide ║ ║ ║ ║ a namespace. ║ ╟───────────────╫───────────────────────────╫─────────────────────────────────╢ ║ superclass ║ module ║ object ║ ╟───────────────╫───────────────────────────╫─────────────────────────────────╢ ║ methods ║ class methods and ║ module methods … Read more
You can do [5, 10].min or [4, 7].max They come from the Enumerable module, so anything that includes Enumerable will have those methods available. v2.4 introduces own Array#min and Array#max, which are way faster than Enumerable’s methods because they skip calling #each. @nicholasklick mentions another option, Enumerable#minmax, but this time returning an array of [min, … Read more
extend – adds the specified module’s methods and constants to the target’s metaclass (i.e. the singleton class) e.g. if you call Klazz.extend(Mod), now Klazz has Mod’s methods (as class methods) if you call obj.extend(Mod), now obj has Mod’s methods (as instance methods), but no other instance of of obj.class has those methods added. extend is … Read more
Like this: sleep(num_secs) The num_secs value can be an integer or float. Also, if you’re writing this within a Rails app, or have included the ActiveSupport library in your project, you can construct longer intervals using the following convenience syntax: sleep(4.minutes) # or, even longer… sleep(2.hours); sleep(3.days) # etc., etc. # or shorter sleep(0.5) # … Read more
This means install the gem, but do not call require when you start Bundler. So you will need to manually call require “whenever” if you want to use the library. If you were to do gem “whenever”, require: “whereever” then bundler would download the gem named whenever, but would call require “whereever” This is often … Read more
I always prefer let to an instance variable for a couple of reasons: Instance variables spring into existence when referenced. This means that if you fat finger the spelling of the instance variable, a new one will be created and initialized to nil, which can lead to subtle bugs and false positives. Since let creates … Read more