Discovering ruby #4

In the ruby koans I now came across array functions. One is collect and I thought, this is map, and the comment below said

'map' is another name for the 'collect' operation

Moving on, I noticed that filter has different names too:

'find_all' is another name for the 'select' operation

So I need to hammer new names in my head and actually also map them and not forget that they are aliases for each other. Better or not, I can't say. I got used to filter and map.

• map can be: collect
• filter is: find_all or select
• reduce is: inject(start_value)

Iterators, yield

Somehow I have to say that the way iterators are used in ruby makes them seem way more simpler and intuitive to use than I know them from ES6.

def many_yields
  yield(1)
  yield(2)
end

many_yields { |item| result << item } 

Maybe it's because the block syntax is so not-like-a-function. And inside the many_yields method you can use block_given? to find out you had been called with a block. Quite handy.

ensure for a method

I have just seen this constructor for the first time, in the koans

def find_line(file_name)
  file = open(file_name)
ensure
  file.close if file
end

Wow, this is so cool, if we don't misuse it. Ensure that a certain block of code is always executed at the end of a function, no matter which execution path was taken.