In C and C++, string literals next to each other are concatenated. As these languages influenced Ruby, I’d guess it inherits from there. And it is documented in Ruby now: see this answer and this page in the Ruby repo which states: Adjacent string literals are automatically concatenated by the interpreter: “con” “cat” “en” “at” … Read more
As has been mentioned: expect(4).to eq(4) This is specifically testing the value that you’ve sent in as the parameter to the method. When you’re trying to test for raised errors when you do the same thing: expect(raise “fail!”).to raise_error Your argument is evaluated immediately and that exception will be thrown and your test will blow … Read more
From within a Ruby script, you can redirect stdout and stderr with the IO#reopen method. # a.rb $stdout.reopen(“out.txt”, “w”) $stderr.reopen(“err.txt”, “w”) puts ‘normal output’ warn ‘something to stderr’ $ ls a.rb $ ruby a.rb $ ls a.rb err.txt out.txt $ cat err.txt something to stderr $ cat out.txt normal output
Use Regexp.union to combine them: union(pats_ary) → new_regexp Return a Regexp object that is the union of the given patterns, i.e., will match any of its parts. So this will do: re = Regexp.union(prefixes) then you use re as your regex: if name.match(re) #…
__FILE__ and __LINE__ are sort of dynamic constants that hold the file and line that are currently executing. Passing them in here allow errors to properly report their location. instance_eval <<-end_eval, __FILE__, __LINE__ def foo a = 123 b = :abc a.send b end end_eval foo When you run this $ ruby foo.rb foo.rb:5:in `send’: … Read more
This is because attributes/associations are actually methods(getters/setters) and not local variables. When you state “parent = value” Ruby assumes you want to assign the value to the local variable parent. Somewhere up the stack there’s a setter method “def parent=” and to call that you must use “self.parent = ” to tell ruby that you … Read more
You can run system call like this: `sleep –help` Or like this system “sleep –help” Or %x{ sleep –help } In case of system it will print output and return true or nil, other two methods will return output PS Oh. It is about displaying in real time. So. You could use something like this: … Read more
You can define a new class in your application at lib/ext/string.rb and put this content in it: class String def to_magic “magic” end end To load this class, you will need to require it in your config/application.rb file or in an initializer. If you had many of these extensions, an initializer is better! The way … Read more
Use rvmsudo command instead of sudo
For a simple solution, use OpenStruct: require ‘erb’ require ‘ostruct’ namespace = OpenStruct.new(name: ‘Joan’, last: ‘Maragall’) template=”Name: <%= name %> <%= last %>” result = ERB.new(template).result(namespace.instance_eval { binding }) #=> Name: Joan Maragall The code above is simple enough but has (at least) two problems: 1) Since it relies on OpenStruct, an access to a … Read more