In this post we will see how to create a custom stream filter. Streams, first introduced in PHP 4.3, provide an abstration layer for file access. A number of different resources besides files – like network connections, compression protocols etc. can be regarded as “streams” of data which can be serially read and written to.
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Unpacking binary data in PHP
Working with binary files in PHP is rarely a requirement. However when needed the PHP ‘pack’ and ‘unpack’ functions can help you tremendously. To set the stage we will start with a programming problem, this will keep the discussion anchored to a relevant context. The problem is this : We want to write a function that takes a image file as an argument and tells us whether the file is a GIF image; irrelevant with whatever the extension the file may have. We are not to use any GD library functions.
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Handling multiple exceptions in PHP 7.1
Exception handling is one of the ways in which modern languages handle errors. PHP usually handles exception in a separate catch block for each different type of exception. Below is a example exception code that uses three custom exceptions ‘MyFooException’, ‘MyBarException’ and ‘MyBazException’ that is later handled in a ‘try’ block.
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Cron Expression Parser in PHP
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.
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PHP 5.5 on Oracle VirtualBox
PHP 5.5 has added a nice support for Generators, which I’ll cover in some other post. I needed to test these new features and add some to old applications. However PHP has dropped support for Windows XP and Windows 2003 starting with PHP 5.5. and I still have a Windows XP machine (along with Ubuntu 14.0 LTS). Although I could install PHP 5.5 in Ubuntu, most of the time I’m using Windows. I decided to go with VirtualBox for installing PHP 5.5, as I have some legacy PHP applications that I want to upgrade to the new version, and VirtualBox makes it easier to switch between operating systems.
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Adding WordPress like shortcodes to your web applications
One of the cool features of WordPress is its shortcode feature. There may be times one wished to add this capability to your PHP web applications. Recently I found one such library which allows you to add shortcode features to your web apps. The library discussed here implements WordPress style shortcode syntax as a standalone package. Its a small package and so can be easily integrated into you existing applications. Content from editors, databases, etc. can be scanned by the Shortcode Manager and the contents replaced by a custom callback.
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Create a quick REST API using Slim framework
During a recent client project, I frequently needed to access a remote database table and update the same for certain fields. This was accomplished using phpMyAdmin on the server. However, it was getting tedious and was prone to accidental updates and deletes. Also, a couple of other developers also needed to make changes to certain fields on the remote database from their local server.
This is all a tedious process and prone to errors. One solution was to create a quick REST api wrapper around the remote database, using which developers could update the database table without any risk of corrupting the data and also with the added benefit of updating the table programmatically.
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