Table class to fill array structure with values

Question

The code creates a table and adds rows and columns.

• Does it make sense to write the code like this?
• Would you design it differently?
• Is there a better OOP approach to this?

class Table attr_reader :grid def initialize(rows: , columns:) @grid = construct(rows, columns) end def construct(rows, columns) raise 'arguments must be arrays' unless rows.is_a?(Array) && columns.is_a?(Array) table = [] rows = [] if rows.nil? rows.each do |row| table << columns.map do |c| c end end table end end 

Here are the specs which describe what it is doing:

require 'spec_helper' require_relative '..\test' RSpec.describe Table do it 'is empty' do table = Table.new(rows: [], columns: []) expect(table.grid).to eq [] end it 'raises if no array is given' do expect { Table.new(rows: [], columns: 1) }.to raise_error RuntimeError expect { Table.new(rows: 1, columns:[]) }.to raise_error RuntimeError end it 'has several rows and columns' do row = double('row') column = double('column') col = Column.new.value = 14 table = Table.new(rows: [1, 3, 3], columns: [1, col]) expect(table.grid).to eq [ [1, 2], [1, 2], [1, 2] ] end end 

Answer 1

Refactored Code

This is a possible way to refactor the code to meet the style guidelines of Ruby using Rubocop.

# frozen_string_literal: true # A simple table with rows and cols class Table attr_reader :grid def initialize(rows:, columns:) @grid = construct(rows, columns) end def construct(rows, columns) unless rows.is_a?(Array) && columns.is_a?(Array) raise 'arguments must be arrays' end table = [] rows = [] if rows.nil? rows.each do |_row| table << columns.map { |c| c } end table end end 

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Style Considerations

A guard clause should be appended wih an empty line. Also, since the line is over 80 characters, split it up in multi-line.

raise 'arguments must be arrays' unless rows.is_a?(Array) && columns.is_a?(Array) table = [] 

unless rows.is_a?(Array) && columns.is_a?(Array) raise 'arguments must be arrays' end table = [] 

You have an unused block argument row and the map should be rewritten using {..}.

rows.each do |row| table << columns.map do |c| c end end 

rows.each do |_row| table << columns.map { |c| c } end 

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General Guidelines and Conventions

The tool also complained about the following guidelines.

• use 2 instead of 4 white spaces for indentation
• remove any trailing white space
• remove space before comma
• add a frozen string literal comment justification
• add top level class documentation comment