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TopTal.com:
Introduction to Objects and References in PHP Memory
Oct 19, 2017 @ 14:50:07

In this new tutorial on the TopTal.com site author Agustin Villalba takes an in-depth look at how objects and references are handled in memory by the PHP language.

In this article, I will talk about how object and variable references are controlled in memory, since this is an issue that can generate discussion and differing opinions. One question to ponder is: “By default, are objects passed by reference or by copy in PHP?” I’m going to talk first about what references are not in PHP; secondly, I’ll discuss what they are, and finally, I will examine how the garbage collector works in PHP.

He starts with a quick comparison between objects and references (since they're slightly different). He then covers what things are and aren't references in PHP and some examples showing what they are in either case. Code examples and visuals are included showing how things relate. The post wraps up with a look at how garbage collection works with objects/references and a few closing thoughts about how the collector chooses which to clean up.

tagged: object reference memory tutorial introduction language garbagecollector

Link: https://www.toptal.com/php/objects-references-php-memory

Alejandro Celaya:
Properly passing data from outer layers of a PHP application to the use case layer
Oct 17, 2017 @ 09:14:57

Alejandro Celaya? has a post to his site sharing some of his experience and advice about how to properly pass data from the outer layers of an app to the "use case" layer. In this situation, the "use case" layer is where most of the processing is happening (versus controllers, views, etc).

Lately, I've been digging a lot in different ways of improving software architecture. Mainly subjects like Clean Architecture, Domain Driven Design, and such.

Those topics cover a lot of advanced and complex practices, but today, I want to talk about a simpler subject. What is the best approach to pass data from outer layers of the application (actions, controllers, async jobs, CLI commands...) to services that are part of the use case layer, by taking advantage of some of the practices promoted by those subjects.

That's a task which is present in any kind of application and is very important to get properly done. You usually need to get data from different origins (a HTTP request, the input of the command line...), filter and validate it, and then use it to perform some kind of task.

He starts off by talking about some of his own previous attempts, starting with a tweet asking where filtering and validation should happen in applications. He then talks about a better approach that makes use of value objects for moving data between service layers. He then walks through a more real-world example (case study) making use of these value objects to handle a user password change.

tagged: passing data tutorial valueobject object layer processing validation filtering

Link: https://blog.alejandrocelaya.com/2017/10/16/properly-passing-data-from-outer-layers-of-a-php-application-to-the-use-case-layer/

Ross Tuck:
Precision Through Imprecision: Improving Time Objects
Aug 10, 2017 @ 11:29:04

In a recent post to his site Ross Tuck looks at improving time objects with imprecision, basically determining the granularity you require and using that in all time operations.

When modeling important numbers, it’s considered good form to specify the precision. Whether it’s money, size or weight; you’ll typically round off to a given decimal point. Even if it’s only for user display, rounding off makes the data more predictable for manipulation and storage.

Unfortunately, we don’t often do this when handling time and it bites us in the rear.

He gives an example of a use of the DateTime handling in PHP and possible inconsistencies when working with the time portion. He offers three possible solutions: one where the time is specified correctly, making a relative modification on the object being checked and, his ultimate solution, just "throwing away" the time and not worrying about it. He then shows how to encapsulate this checking and a few other issues that can come with date/time and evaluations (like equals checks).

tagged: datetime imprecision time object date tutorial

Link: http://rosstuck.com/precision-through-imprecision-improving-time-objects

thePHP.cc:
Don't call instance methods statically
Jul 25, 2017 @ 11:16:39

In this new post on thePHP.cc site they talk about calling instance methods statically, more specifically that it should be avoided.

There are quite a few things in PHP 4 that were a bit strange. One example is that PHP 4 allowed static calling of instance methods. [...] To keep backwards compatibility with PHP 4, this code works up to PHP 5, even though [the method in the example[ is not declared static.

[...] Now things will get really weird. When calling an instance method of another class statically, the $this context would carry over from the caller to the called class. In other words, $this suddenly refers to another object instance. While in PHP 5, this used to be an E_STRICT error, PHP 7 will emit an E_DEPRECATED error.

They point out that, while this is definitely odd behavior that shouldn't exist, it hasn't been removed because of PHP's backwards compatibility principles and only removing functionality like this in major versions. So, instead, they recommend calling all non-static methods using an instance of the class injected rather than directly calling them.

tagged: instance method call static object avoid error

Link: https://thephp.cc/news/2017/07/dont-call-instance-methods-statically

Laravel News:
Laravel 5.5 Custom Validation Rule Objects
Jul 17, 2017 @ 10:20:40

On the Laravel News site there's an article covering custom validation objects and using them in a Laravel-based application. This validation handling is added in Laravel v5.5 (upcoming as of the time of this post) to allow for easy extension of current validation rules.

Laravel 5.5 will introduce support for custom validation rule objects as an alternative to using Validator::extend for custom validation rules.

To define a custom validation rule, implement the IlluminateContractsValidationRule interface or use a Closure. The custom rule is then used directly in a validator.

They provide a few examples of defining these objects, using the "passes" and "message" methods defined in the interface. It also shows how to put them to use in a "validate" call on a request using both the object and closure versions. This new custom validation handling helps to replace some of the difficulty with the previous extension methods and makes it more flexible by allowing closures.

tagged: laravel custom validation object introduction closure tutorial

Link: https://laravel-news.com/custom-validation-rule-objects

Simon Holywell:
PHP and immutability - part two
Apr 04, 2017 @ 12:54:48

Simon Holywell has continued his series looking at immutability and PHP in part two of his series improving on the code and classes from the previous post.

In the last article we learnt how to create an immutable data structure in PHP. There were a few issues to work through, but we got there in the end. Now onto making the immutable class more useful and easier to create modified copies. Note that these are copies and not modifications, in-place, to the original objects.

He then moves on from the "simple" mutation method previously used (making a new immutable object when a property changes). When the property list starts getting more complex simple single value references no longer scale. He makes use of methods internal to the class to modify the values and return a new immutable instance with the updated value. He shows how to modify this to prevent the setting of unexpected properties and how to expand it out to allow the input of an array of values to update and how to handle required/optional property values.

tagged: immutability series part2 tutorial immutable object

Link: https://www.simonholywell.com/post/2017/04/php-and-immutability-part-two/

Robert Basic:
PHP traits to create test doubles
Apr 04, 2017 @ 10:47:15

In a new post to his site Robert Basic shows how to make use of traits to create test doubles in your unit testing practice. He sees them as a simple method for keeping tests clean and not having mocks/fakes/etc. all over.

Keeping your application or library code well organized, easy to follow, and read is important. Your test code should not be exempt from those rules, you should follow good testing conventions.

One part of my tests that I feel like that are out of control are the test doubles. Dummies, fakes, mocks… Seems like they are everywhere and that I keep writing the same ones over and over again. I do follow some good practices on how to reduce code duplication in my tests, but these mocks… Ugh.

He starts with a simple example, showing a test that evaluates the result of a transaction being executed (true or false). However, he describes the eventual "creep" of the tests as more are added and, with each, more "transaction" object instances are required. He suggests refactoring the creation of those doubles into traits where the class they're called from can inherit them and test setup is a bit cleaner. He proposes a "trait for every double" so that they can be easily included as needed and without conflict.

tagged: traits unittest double mock tutorial example setup object

Link: https://robertbasic.com/blog/php-traits-to-create-test-doubles/

Benjamin Eberlei:
Explicit Global State with Context Objects
Mar 24, 2017 @ 11:50:12

In a post to his site Benjamin Eberlei looks at global state in PHP using something called "context objects" and how they can be used as an alternative to true global state.

Global State is considered bad for maintainability of software. Side effects on global state can cause a very nasty class of bugs. Context objects are one flavour of global state. For example, I remember that Symfony1 had a particularly nasty context object that was a global singleton containing references to very many services of the framework.

As with every concept in programming, there are no absolute truths though and there are many use-cases where context objects make sense. This blog posts tries to explain my reasons for using context objects.

He starts by getting everyone on the same page by defining a context - the "circumstances in which something can be fully understood". He then moves into the world of context objects, talking about how they encapsulate the information other objects need to execute. They're essentially "container" objects that allow for more control that something like the normal PHP superglobals. From there he helps you define what kind of context objects you might need in your application and provides a real-world example from his own experience at Tideways.

tagged: global state context object tutorial introduction definition

Link: https://beberlei.de/2017/03/12/explicit_global_state_with_context_objects.html

Mark Baker:
Closure Binding as an alternative to “use” variables
Mar 13, 2017 @ 09:56:56

Mark Baker has posted a tutorial to his site showing how to use closure binding as an alternative to "use" when calling closures in your PHP application.

As a general rule when creating a Closure, arguments are passed when the function is called, but “use” variables (I’m sure that they have a formal name, but have no idea what it might be, so I just refer to them as “use” variables because they’re passed to the Closure through a “use” clause) are fixed as the value that they already contain when the Closure is defined, and the variables themselves must already exist within that scope

[...] Of course, the drawback of this approach is that when we need to change the price minimum and maximum values for filtering, they’re hard-coded in the callback.

He talks about the limits this imposes on calling the closure (ex: can't easily add addition params) and how the values have to already exist before the closure can be called. He points out that calling the variables by reference can help somewhat but it still comes with some of the same baggage. He then shows how to use object binding for a closure to handle the same kind of "min" and "max" by working around it with a closure bound internally to an object and called via a public method.

tagged: closure bind variable object tutorial use

Link: https://markbakeruk.net/2017/03/12/closure-binding-as-an-alternative-to-use-variables/

QaFoo Blog:
Extracting Data Objects
Feb 10, 2017 @ 12:16:36

On the QaFoo blog they have a new post offering some advice on extracting functionality to data objects and reducing the complexity of your application's interfaces.

Extracting data objects from your code will make it easier to read and write, easier to test and more forward compatible. This post shows you the two most common cases where introducing a data object makes sense and how to do it.

The first case covers the extraction when a method ends up with too many parameters. We've all been there and remembering the correct order and values for each (not to mention optional vs required). By making use of value objects you can reduce that down to one or two parameters that act as self-contained "containers" for the same values. They illustrate with a refactor of "product" search criteria into a "ProductCriteria" object. The second example show a refactor away from using an array as an input value and providing a bit more structure with a "Checkout" value object instead.

The post ends with a helpful hint about migrating from one method to the other in legacy systems using a "shim" method to handle the new case right alongside the old one.

tagged: data object refactor simplicity parameters array

Link: https://qafoo.com/blog/096_refactoring_extract_data_objects.html