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Laravel News:
Working with Mutable and Immutable DateTime in PHP
May 30, 2018 @ 09:34:51

On the Laravel News site there's a tutorial posted showing how to work effectively with mutable and immutable DateTime functionality in PHP. The DateTime functionality has long been bundled with the language and offers powerful tools for working with dates, improving on what the basic date function provides.

Mutable dates can be the source of confusion and unexpected bugs in your code. My goal isn’t to tell you that DateTime is evil because it’s mutable, but to consider the tradeoffs and benefits of using mutable versus immutable DateTime objects. Either approach warrants a good test suite and an awareness of how modifier methods affect your date objects.

Until recently, I wasn’t even aware that PHP offers a counterpart to the DateTime class: DateTimeImmutable. The DateTimeIummtable class works just like the DateTime class, except that it never modifies itself, but returns a new object instead. So if you know how to work with DateTime, you immediately can work with DateTimeImmutable.

The article starts by talking about mutable DateTime objects and shows examples of using the Carbon date handling package as a layer on top of PHP's DateTime handling. It includes code examples of mutable objects. It then moves on to the immutable objects, covering the differences between the two complete with code examples. The post ends with a bit more information about mutable vs immutable and links to the Chronos documentation for more information on another date handling library.

tagged: datetime tutorial carbon package mutable immutable

Link: https://laravel-news.com/mutable-and-immutable-date-time-php

Frank de Jonge:
Being in control of time in PHP
Mar 08, 2018 @ 10:49:18

Frank de Jonge has a new post to his site covering something that always seems to be a difficult topic in development: time. In his post he suggests that date and time handling in your application is a "dependency" that could be difficult test.

When developers talk about the infrastructural boundaries or external dependencies they often talk about databases and third-party integration. They're the first thing we'll put behind an interface so we can stub them out during our tests. This gives us some control over them. It's become relatively easy to spot these dependencies because we do it frequently. They're the usual suspects.

However, some "dependencies" are much harder to spot. They even live right inside the standard library of PHP and often manage to seep through the cracks. Date/Time handling is such a thing. So what's the problem and how do we fix it?

He goes on to talk about date/time handling programming languages in general and how its variance can can cause issues that might be out of our control. He suggests that when time "gets the best of you" you should opt to be more specific in your date/time handling (the cause is usually precision). He then gets into some code examples of how to "control time" by reducing the impact that direct date/time handling could have on your application. He also includes an example of testing this handling and finishes with the idea of "consuming time as a service".

tagged: datetime control test unittest example dependency

Link: https://blog.frankdejonge.nl/being-in-control-of-time-in-php/

Derick Rethans:
Mar 06, 2018 @ 10:28:20

In a new post to his site Derick Rethans talks about "analemmas" and shows how to use PHP's own DateTime handling to determine the locations of the sun at different intervals (that's what an "analemma" tracks).

Last week I listened to an The Sceptics' Guide to the Universe where the word of the week was "But as I am currently starting to update the Guide to Date and Time Programming for a second edition, I was wondering whether I could create an analemma from existing PHP functions. Unfortunately, PHP only provides functionality to calculate when the Sun is at its highest point, through date_sun_info().

He includes an example of this function in use to determine the time the sun was at its zenith. While PHP by itself can't calculate the position, Derick remembered a PHP extension he wrote that could help: php-solarsystem. He includes some code using this functionality to iterate and locate the sun via its azimuth and altitude based on his choice of location (London). The result is a CSV export of data that he then drops in to gnuplot to create the graph of the analemma during that time.

tagged: analemma sun location diagram extension tutorial datetime graph calculate

Link: https://derickrethans.nl/analemma.html

Robert Basic:
Creating datetimes from a format with a timezone
Oct 17, 2017 @ 10:49:54

Robert Basic has a quick post to his site sharing a method he uses for creating datetimes from a format with a timezone. In his examples, he makes use of the createFromFormat handling in PHP's DateTime functionality to more correctly handle processing strings with timezone offsets rather than a DateTimezone parameter.

I wouldn’t be writing this blog post if I’d read all the “fineprints” in the PHP manual. Alas, here we are.

The DateTime and DateTimeImmutable classes have a createFromFormat method. As you can probably guess from its name, it creates a datetime object from a datetime string formatted in the specified format. [...] When the format has a timezone offset though, that’s… the part I skipped in the manual.

He found that the createFromFormat handling ignores the provided timezone as the optional third parameter if there's an offset included with the date/time string to parse. No error is thrown, it just silently ignores the third parameter and sets the "timezone" value of the resulting object to an odd value.

tagged: datetime offset optional tutorial timezone

Link: https://robertbasic.com/blog/creating-datetimes-from-a-format-with-a-timezone/

Derick Rethans:
New Date/Time Support in MongoDB
Aug 15, 2017 @ 09:46:11

In a new post to his site Derick Rethans talks about the new DateTime support in MongoDB and includes some PHP examples showing the changes in action.

In the past few months I have been working on adding time zone support to MongoDB's Aggregation Framework. This support brings in the timelib library that is also used in PHP and HHVM to do time zone calculations.

He then splits the rest of the post up into parts for the changes that this integration brings:

  • Time Zone Support for Date Extraction Operators
  • The $dateToParts Operator
  • The $dateFromParts Operator
  • Changes to the $dateToString Operator
  • The $dateFromString Operator
  • Using Date Expressions in $match

The post ends with a few notes about these changes, noting that it's currently only in the development release and "should be considered experimental" and subject to change. He then points out a few issues that will probably require updates to these features.

tagged: datetime support mongodb example tutorial list

Link: https://derickrethans.nl/mongo-date-time.html

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

Education Station: Simple, Compact Time Range Creation with Period
Jul 18, 2017 @ 10:08:48

php[architect] magazine has shared a column from their July 2017 issue, "Education Station" by Matthew Setter, looking at the use of Period for date and time handling.

For the longest time, I’ve enjoyed using PHP’s DateTime library. I’ve always found it to be relatively straightforward in creating DateTime objects for use with various applications I’ve written.

However, one thing that isn’t very simple, nor intuitive, is the ability to create time ranges—especially ones requiring some degree of sophistication, such as fiscal quarters, for financial reporting requirements. [...] It’s for [code reuse] reasons that I’m going to spend the [end] of the column introducing Period, a Time range API for PHP, maintained by The League of Extraordinary Packages.

He starts off by showing how to do things "the hard way" with the built-in PHP DateTime handling and how difficult it can be to work with ranges. In his example he tries to get the dates for a "quarter", a portion of a year usually used for business reporting purposes. He works through some of the issues he faced during the date calculations and things lie leap years and odd date ranges. He then introduces Period as a way to help solve some of these problems. He lists out the main goals of the project, installing the package and using it to get the same "quarter" dates as his attempt before.

tagged: educationstation column matthewsetter phparchitect july2017 issue period datetime

Link: https://www.phparch.com/2017/07/education-station-simple-compact-time-ranges/

Zend Developer Zone:
Scheduling ElePHPants (DateTime math is HARD)
Nov 18, 2016 @ 12:49:38

On the Zend Developer Zone there's a new post talking about scheduling in applications ("scheduling elePHPants") including both library recommendations and advice about code reuse.

It was while I was creating the 100th or so cronjob to do some very similar to the other 99 that I thought, “Hey! Why not just put all this in a database and check it once a minute instead?” [...] It would be so much easier to deal with in PHP. Also, cron does not scale well at all either in performance or management.

The problem is that cron is an elegant solution for “Do this at that time” type of problems. Every solution I came up with was basically re-creating cron. That in itself isn’t a bad thing, but the logic involved in doing what cron does is mind-melting.

[...] Then it hit me, I am probably not the first person that has had this need. There have probably been other people who needed to implement “Do this at that time” within a PHP application. So I started looking around. What I found was encouraging.

The author then mentions several packages that he went through searching for the right solution to his problem, noting that while Laravel-based solutions seemed nice, they wouldn't work with his framework choice (Slim). He decided on the cron-expression package, finding it to be the best fit for the project's needs.

I had spent countless hours trying to create the solution myself. [...] I got so lost in solving the problem, I forgot to look to see if someone had already solved it. [...] After I finally came to my senses, I tweeted that out to remind myself to “Use the Source”.
tagged: schedule task cron experience package code reuse datetime

Link: https://devzone.zend.com/7418/scheduling-elephpants-datetime-math-is-hard/

Ignace Butera:
DatePeriod demystified
May 17, 2016 @ 12:16:37

Ignace Butera has shared a post to his site giving some advice about using the DatePeriod functionality from PHP's DateTime handling. The DatePeriod makes it easier to work with dates at certain intervals without having to calculate them manually.

With the introduction of the DateTimeImmutable object in PHP5.5, and a subsequent bug fix to DatePeriod in PHP5.5.8, the object results became rather interesting. To sum it up, when iterating over a DatePeriod, the datepoint returned is of the same instance as the starting datepoint. Let’s illustrate this by taking the first example and using a DateTimeImmutable object instead as the starting datepoint.

The post starts with a brief overview of the DatePeriod functionality and a code example of it in use (along with two DateTime objects for start/end dates). He shows how it returns DateTimeImmutable objects and the properties they expose to get more information about the objects. He points out a few buggy points in the API, though, and makes a recommendation of a library that's a bit more consistent.

tagged: datetime dateperiod example introduction api

Link: http://nyamsprod.com/blog/2016/dateperiod-demystified/

SitePoint PHP Blog:
Suggesting Carbon with Composer – Date and Time the Right Way
Nov 16, 2015 @ 09:16:58

On the SitePoint PHP blog there's a tutorial that's been posted spotlightling a PHP library that can make working with dates and times simpler: Carbon . In this new tutorial they walk you through what the library has to offer and plenty of examples of it in use.

Carbon is a small library for date and time manipulation in PHP. It relies on and extends the core DateTime class, adding helpful methods for a significantly saner experience.

In this article, we’ll take a look at some basic usage examples, and then use it in a real project.

They start with the installation (via Composer) and a few examples of it in use, determining if a given date string is a weekend, in a leap year, etc. They also talk about localization support and working with time intervals. He then gets into the more real-world part of the example, updating the Diffbot client to optionally support Carbon for its date/time handling. He starts with some tests to define how he wants the handling to work and how to use it to parse the date returned from the DiffBot API.

tagged: carbon datetime library tutorial date time diffbot client api

Link: http://www.sitepoint.com/suggesting-carbon-with-composer-date-and-time-the-right-way/