City Office #

Welcome to City Office on Exercism's PHP Track. If you need help running the tests or submitting your code, check out HELP.md. If you get stuck on the exercise, check out HINTS.md, but try and solve it without using those first 😃

Introduction #

Type Declaration #

Type declarations in PHP provide type assertions at run time for function arguments, return values and class properties. On functions, a void return type can be added to indicate that no value is returned from the function. Declared types also serve as run time assertions that functions are returning a reasonably typed response.

<?php

class Driver
{
    private int $serial_number;

    public function setSerialNumber(int $number): void
    {
        $this->serial_number = $number;
    }

    public function getSerialNumber(): int
    {
        return $this->serial_number; 
    }
}

$driver = new Driver();
$driver->setSerialNumber("Version 1b"); // This will throw a TypeError

Type Unions #

If a function argument, return value or class property can be more than one type a type union may be declared.

<?php

class IdentityCard
{
    private int|null $id = null;

    public function assign(int|float $id): void
    {
        $this->id = intval($id);
    }
}

$card = new IdentityCard();
$card->assign(5.0);

Mixed Types #

Instructions #

You have been working in the city office for a while, and you have developed a set of tools that speed up your day-to-day work, for example with filling out forms.

Now, a new colleague is joining you, and you realized your tools might not be self-explanatory. There are a lot of weird conventions in your office, like always filling out forms with uppercase letters and avoiding leaving fields empty.

As a first step you decide to add PHP type declarations so that it is easier for your new colleague to hop right in and start using your tools.

1. Declare the types for the Address class #

Add property type declarations to each of the Address class properties declared. Each class property should be declared as a string.

2. Declare the types to fill out the form with blank values #

Add a parameter type declaration and a return type declaration to the blanks method in the Form class. The method should take in an integer length, and return a string representation of the blank line.

3. Declare the type when splitting a value into separate letters #

Add a parameter type declaration and a return type declaration to the letters method in the Form class. The method should take in a string, representing words, and return an array of letters.

4. Declare the type when checking if a value will fit into a form #

Add parameter type declarations and a return type declaration to the checkLength method in the Form class. The method should take in a string word, and an integer maximum length, and return a true or false value.

5. Declare the type when formatting an address in the form #

Add a parameter type declaration, making use of the Address class updated previously, and a return type declaration to the formatAddress method in the Form class. The method should take in an Address and return a formatted string.

Source #

Created by #

@neenjaw