Leanpub: Publish Early, Publish Often

3. Development tools

So far we’ve outline some of the basics of using PHP without a web server, but before we really get into the nitty-gritty details of developing useful non-web software we’re going to take a slight detour into the world of PHP development tools. This is for two reasons. Firstly, before deciding which techniques and methods you are going to use (Interactive CLI script or GUI interface) it is important to understand what tools are available to help support your choice of programming methodology. Secondly, you will often need to adopt a different workflow when developing a new type of software that you may not be familiar with, so you may need to find new tools to fit your new way of working.

In general, you can use the same development tools for general purpose programming as you do for web development, after all PHP syntax is the same wherever it’s executed. The main differentiator is your workflow, and you may find yourself being more productive with different tools.

Of course one of PHP’s dirty secrets is that many PHP programmers don’t use debuggers, unit testing, build systems or code profilers, and in many cases don’t even know what they are. Usually it’s because many PHP scripts are developed as small, uncomplicated, low-risk projects by single developers, and the overhead of learning and deploying extra tools is an unnecessary burden (particularly for those without a formal computer science or programming education). Don’t worry if you fall into this camp, we’ve all been there (and like to visit from time to time!).

However when you start venturing into general purpose programming, you’ll find that the complexity of projects often increases. Rather than a selection of short lived scripts with limited shared state executing in less than a second, you’ll get into larger code bases with longer running processes and more complex dependencies. In such scenarios, the effects of bugs can be magnified and tracking them down becomes increasingly hard. Code is revamped less often and can be relied upon by an organisation and remain deployed for much longer, increasing the burden of maintaining code in the future. If you’re not a regular user of the type of tools described in this chapter, you might find this the ideal opportunity to delve into the wider world of PHP development tools, and give yourself a good foundation on which to start building real software.

We’ll look in turn at different classes of tool, and give some examples of, and links to, popular tools of each type.

3.1 PHP REPLs

When you want to test out a few lines of PHP, your default instinct may be to create a new PHP file, save it, and then execute it with PHP. There is a better, faster and more interactive, way however. The PHP “Interactive Shell”, also known as the PHP REPL (Read-Eval-Print-Loop), is a quick and easy way to type in code and have it execute immediately. Unlike executing single lines of code using php -r, the REPL (started by calling php -a) keeps the scripts state (e.g. contents of variables and objects) in-between each line that you type, until you exit. You can use all of PHP’s functions, although no libraries are loaded by default, and you can include() or require() existing files of PHP code. This latter capability is useful for debugging the final output of a problematic script; simply include() your script which will execute the script and, as long the script doesn’t terminate prematurely, then you can echo() or print_r() or otherwise explore the state of the variables and other resources at the end of the run. The following example is a capture of an actual interactive REPL session using the standard PHP REPL. Other brands of REPL are available, and are listed later in this section.