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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/

Simon Holywell:
International PHP dates with intl
Jul 22, 2015 @ 12:55:33

Following up on his previous post about date/time handling and localization, Simon Holywell has posted an update with information about using the "Intl" extension for PHP to get it working with the more powerful PHP DateTime handling.

I wrote about localising dates (and other data) in a recent blog post, but unfortunately there were some shortcomings where time zones were concerned. As I alluded to in that post there is a way around this via the Intl extension that exposes a simple API to format DateTime instances. Thankfully this follow up post will be quite short as the setup is very simple for those of you on Ubuntu/Debian you can use the repositories.

He includes the commands you'll need to install the extension (via apt-get), compile it via the "pecl" command and update your php.ini file to enable it. He also includes some code examples showing how to use the IntlDateFormatter handling to work with dates, formats and calendars.

tagged: international datetime intl extension tutorial aptget pecl

Link: https://www.simonholywell.com/post/2015/07/international-php-dates-with-intl/

Sameer Borate:
Cron Expression Parser in PHP
Jul 21, 2015 @ 10:15:09

If you've ever worked with the "cron" tool on a unix-based system, you know that there's a special syntax that comes along with defining when the commands should run. It can be difficult to get this timing exactly right, especially if you're very picky about the execution time. In this post from Sameer Borate he shows you a PHP library that can help not only parse current cron configurations but also provides shortcuts for common timings (ex: "daily" or "weekly").

Working with cron scheduling can many times be a frustrating affair. Although setting a few cron jobs at one time can be easy, calculating cron dates in the future in code can get time consuming quickly. The PHP cron expression parser described here can parse a CRON expression, determine if it is due to run, calculate the next run date of the expression or calculate the previous run date of the expression. You can calculate dates far into the future or past by skipping n number of matching dates.

He includes some examples of putting the library to use to define a cron object based on an expression (either via a shortcut or an actual cron time expression). You can then check to see if the cron is "due" or perform some various operations about its run dates. This includes a formatted output of the previous run time, the next run time and the calculation of the next/previous run time based on a relative timestamp.

tagged: cron parser library example tutorial run due evaluation datetime

Link: http://www.codediesel.com/php/cron-expression-parser-in-php/

Giorgio Sironi:
Property-based testing primer
Jun 19, 2015 @ 12:15:29

Giorgio Sironi has a new post to his site today talking about a method (and tool) around a different sort of testing practice: property-based testing. The difference is that, instead of hard-coding values and evaluating them post-processing, you're generating random values and ensuring they match against a set of properties, not values.

I'm a great advocate of automated testing and of finding out your code does not work on your machine, 30 seconds after having written it, instead of in production after it has caused a monetary loss and some repair work to be performed. [...] However, classic test suites written with xUnit and BDD styles have some scaling problems they hit when you want to exercise more than some happy paths. [...] Property-based testing is an approach to testing coming from the functional programming world.

He helps to make the point a bit more clear with an example of testing the "sort" function and its results. He talks about how to test it using normal data, empty data, etc. but notes that this kind of testing can become "boring and error-prone". Instead he proposes the property-based testing of the results. He generates random values to feed into the method and checks to ensure the results are sorting by comparing them to each other. He expands this with a bit more complex example, showing how to test some DateTime handling and evaluating the result with logic in a closure. To help make this kind of testing easier, he's created a library (Eris) that extends PHPUnit and provides the methods seen in his examples.

tagged: property testing unittest phpunit extension random datetime sort eris

Link: http://www.giorgiosironi.com/2015/06/property-based-testing-primer.html

Sameer Borate:
Period: Time range API for php
Nov 05, 2014 @ 10:55:28

In his latest post Sameer Borate looks at a library he's recently found that's helpful for working with dates and times, even easier than the DateTime handling built into PHP. The Periodlibrary, part of The League of Extraordinary Packages, aims to "resolve many recurrent issues around time range selection and usage."

Date/time programming is one of the tricky aspects of software development. Although inherently not complex in itself, coding date/time algorithms can be a subtle source of bugs. Especially in web development a feature such as payment subscription processing that ranges from days to weeks to months can get complex quickly. Also such kind of scenarios require additional features like auto renewal, scheduled email alerts to subscribers etc. Such kind of features require good date/time handling algorithms and libraries that handle such chores are always welcome. One such library I encountered recently is Period.

He walks you through the basics first - getting the library installed and creating a new instance of the class to work with. He goes through each of the methods available including the constructor, getting the duration between times and getting the start/end values back as DateTime objects. He also looks at the methods that allow you to create the ranges from various time frames (quarters, weeks, etc), compare ranges and modify time ranges that already exist.

tagged: time range library period leagueofextraordinarypackages datetime

Link: http://www.codediesel.com/algorithms/period-time-range-api-for-php/

Evert Pot:
PHP 5.5.10 timezone handling changes
Mar 31, 2014 @ 12:29:27

Evert Pot has a new post sharing some of the changes in DateTime handling that he's updated in the latest release in the PHP 5.5.x series.

PHP 5.5.10 got released a few weeks ago, and among other things, it added some new functionality related to timezone handling. In short, [subtracting from UTC] now works. Normally this would not be recommended, as you really should specify timezones based on their geographical location. This information is not always available though, so it's a welcome new feature.

Other changes include the removal of the automatic translation from "UTC" to "GMT" as well as errors being thrown when one of the "odd" timezones are used (he provides the list). Additionally, an update around timezone "guessing" has been added and the fallback that was in place has been removed.

tagged: timezone change datetime utc gmt error names

Link: http://evertpot.com/php-5-5-10-timezone-changes/

Derick Rethans:
DateTimeImmutable
Feb 26, 2014 @ 10:26:45

In his latest post Derick Rethans (knower of all things date and time) talks about the DateTimeImmutable functionality. It has been added into the PHP 5.5 releases and provides the same DateTime functionality but removes the ability for modification (mutability).

The first time that my improved DateTime support made its way into PHP was officially in PHP 5.1, although the more advanced features such as the DateTime class only made it appearance in PHP 5.2. Since its introduction the DateTime class implementation suffered from one design mistake - arguably not something that even an RFC would have highlighted. [...] This mutability property that all modifying methods of the DateTime class have is highly annoying, and something that I would now rather remove. But of course we cannot as that would break backwards compatibility. So in PHP 5.5, after a few stumbles, I finally managed to rectify this.

He includes some code examples showing the current DateTime object's mutability (via the "modify" function) and the new immutable handling. This new handling doesn't update the current object but instead returns the modified object, leaving the initial one intact. You can find out more about this new object in the PHP manual.

tagged: datetime datetimeimmutable mutability return object php55

Link: http://derickrethans.nl/immutable-datetime.html

NetTuts.com:
Dates and Time - The OOP Way
Oct 24, 2013 @ 11:49:23

On NetTuts.com today there's a new tutorial they've posted showing how to use PHP's DateTime functionality in a more OOP kind of way. The DateTime extension lets you work both ways - procedural and OOP, with only slightly different syntax changes between them.

The Date/Time PHP extension is a set of classes that allow you to work with almost all of the date and time related tasks. It’s been available since the release of PHP 5.2 and the extension introduced several new classes.

The tutorial first shows you some of the differences between just working with something like date and DateTime. From there they get into a bit more complicated things like:

  • Modifying dates/times
  • Working with multiple dates
  • Working with timezones
  • Using DatePeriods
  • Extending the current functionality

There's also two more "real world" usage scenarios included - defaulting to using UTC times and using the DateInterval to handle subscription payment logic.

tagged: datetime tutorial oop introduction date time

Link: http://net.tutsplus.com/tutorials/php/dates-and-time-the-oop-way/