PHP, Deeper

7.3

April 2019

By Loïc Truchot

PHP: Hypertext Processor

-> PHP: Hypertext Processor

Better debugging

bugs
- are inherent in coding
- more frequent in interpreted languages (PHP)
- more frequent in loosely typed language (PHP)
- not related to experience
tools
- Best practices
- A good IDE (linters, prettiers)
- var_dump & XDebug
- RTFM (& Errors !)
- Debuggers

# php.ini
zend_extension=""
xdebug.default_enable=1
xdebug.auto_trace=1
xdebug.profiler_enable=1

Variables Scope

JavaScript

PHP

<script>
    var test = 42;
    function modifyTest () {
        test = 24;
    }
    modifyTest()
    console.log(test);
</script>

<?php
    $test = 42;
    function modifyTest () {
        $test = 24;
    }
    modifyTest();
    var_dump($test);
?>

Who will win ?

step 1

Variables Scope

step 2

scope (or lexical scope) is "where can I use my variable ?"
answer is different for each language
In PHP, the scope of a variable is
- the function, where the variable is declared (local)
  - OR
- everywhere, except in functions (global)

$test = 42;
function testX3 ($val) {
    $result = $val * 3;
    return $result;
}
$test = testX3($test);

a function is like a mini-program, with its own variables
use values in a function ? give it as arguments, and I return the modified value !

Workshop Session

scope

write a function useful to enhance a pizza
- it takes a pizza hashtable with ingredients
- it return an enhanced hashtable
  - if there is some "ham" or "chicken", it add "veg" => false
  - else, "veg" => true

Variables Scope

step 3

access a global variable if a function ?
- add "global $a, $b;" at the beginning of the function

$test = 42;
function testX4 () {
    global $test;
    $test = $test * 4;
}
testX4();
var_dump($test);

so it modify something outside the function
it's called a side effect
it's bad and you should feel bad

$test = 42;
function testX5 (&$var) {
    $var = $var * 4;
}
testX5($test);
var_dump($test);

you can achieve the same with reference "&"
value vs reference is a larger purpose
it is a bad practice too, called "impure function"

Workshop Session

scope

use your pizza vegetarian enhancer with a global
use your pizza vegetarian enhancer with a reference
add a "vegan" tag for pizza without meat and cheese (FizzBuzz)
in the "foreach" displaying pizzas :
- display a bootstrap badge for every vegetarian pizza
- display a bootstrap badge for every vegan pizza

To remember

scope is related to the life cycle of a variable
- when & where it was born
- when & where it is usable
- when & where it will die
in PHP, the scope is the function:
- variables can have the same name in/out a function, because it will not be the same variable
you can access global scope (global or &), but it is dangerous
- side effects are out of contol
- side effects are not testables
scope is different regarding programming languages: have to learn it

include / require

Your code needs to be organized
between 100 and 500 lines
how to organize it ?
- one function per file ?
- one class per file ?
- one collection per file ?
- one template
include or require ?
include_once or require_once ?

Workshop Session

inclusion

reorganize the code of our pizzeria
- one folder for templates, on for functions, one for data
- one file for all collections, "require_once"
- one function per file loaded with a "require_once"
- one template per file, by big parts, loaded with include
- what happen if we load several time the same file ?
- add some beautiful responsive structure for site

To remember

every language have an import/export system
PHP offers
- include, to import one or more time, warning any error
- include_once to import only one time, warning any error
- require, to import one or more time, error crashing
- require_once, to import only one time, error crashing
Warning: PHP imports are as it comes, without dependency injection: everything should be logical, well organized, well documented

superglobales

as well as functions, some native globales exists
- $GLOBALS: I already know that
- $_REQUEST, $_GET, $_POST, $_FILES for web requests & forms inputs
- $_SERVER & $_ENV for infos about computer that run PHP
- $_SESSION & $_COOKIE to store infos about users

@see https://www.php.net/manual/fr/language.variables.superglobals.php

Workshop Session

superglobales

try to var_dump some globals: comment the result
add this code to your html in superglobales.php

<form action="superglobales.php" method="POST">
    Name: <input type="text" name="name" />
    <input type="submit" />
</form>

in the same file, display $_POST, and play with the input field. What does it implied ?

forms and $_POST

some words about HTTP protocol & methods
- POST, GET, PUT, DELETE... + PATCH & HEAD
HTML forms are dedicated to this kind of communication
GET for url params
POST for payloads
every data will be in $_POST array, but sometimes formatted (checkbox = "on" || "off")

Workshop Session

forms

create a page dedicated to register our user
name field is required
when user is registered, say hello and list all infos in an HTML table

Workshop Session

forms

create a hangman game
- use HTML hidden inputs
- use PHP function: strpos, str_split, join

AJAX

functions are useful to do some input / output (i/o)
input are often coming from user prompts/forms
AJAX is the best way to get a user input

step 1

function toQuizz($quizz, $rightIndex, $userChoice) {
    if ($quizz[$rightIndex] == $userChoice) {
        return "bravo";
    } else {
        return "error: right answer was" . $quizz[$rightIndex];
    }
}

AJAX

to do some AJAX, we need
- a php file, that will manage the request
- a javascript library that can do some ajax
- a form

step 2

$("#btn").click(event => {
	$.post({ 
		url: "request.php",
		data: { name: $("#ipt").val() },
		success: data => alert(data)
	});
});

<?php 
	$name = $_POST["name"];
	echo "coucou $name !"
?>

Live coding session

AJAX

finaliser le quizz pour qu'il marche avec AJAX
travailler sur un panier pour notre pizzeria

RegExp

rational expressions / regular expression: the nightmare begin
what about a if to check an email ?
how to do that in one line ? the RegExp !
a lot of string native functions in php: use them
preg_match($pattern, $str): check if string valid the condition

<?php
$containTest = preg_match("/test/", "ceci est un test.");
var_dump($containTest);
?>

Live Coding Session

regexp

validate email in our register form
is it possible with AJAX ?

PHP, Deeper

PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

-> PHP: Hypertext Processor

Better debugging

Variables Scope

JavaScript

PHP

Variables Scope

Workshop Session

scope

Variables Scope

Workshop Session

scope

To remember

include / require

Workshop Session

inclusion

To remember

superglobales

Workshop Session

superglobales

forms and $_POST

Workshop Session

forms

Workshop Session

forms

AJAX

AJAX

Live coding session

AJAX

RegExp

Live Coding Session

regexp

other topics