Easier command-line arguments in PHP

Arguments
Photo by Between a Rock

One of my pet peeves is that no language I've used handles command-line arguments well. Everyone falls back to C's original argv indexed array of space-separated strings, even though there's decades-old conventions about the syntax of named arguments. There's some strong third-party libraries that make it easier, and the arcane getopt(), but nothing that's emerged as a standard. Since I'm doing a lot more PHP shell scripts these days, I decided to write a PHP CLI parser that met my requirements:

Specify the arguments once. Duplication of information is ugly and error-prone, so I wanted to describe the arguments in just one place.

Automated help. The usage description should be generated from the same specification that the parser uses so it stays up-to-date.

Syntax checking. I want to be able to say which arguments are required, optional or switches, and have the parser enforce that, and catch any unexpected arguments too.

Unnamed arguments. Commands like cat take a list of files with no argument name, I wanted those to be easily accessible.

Optional defaults. It makes life a lot easier if you don't have to check to see if an argument was specified in the main script, so I wanted to ensure you could set defaults for missing optional arguments.

Human-readable specification. getopt() is close to what I need, but as well as not generating a usage description, the syntax for describing the long and short arguments is a horrible mess of a string. I want the argument specification to make sense to anyone reading the code.

Here's the result, cliargs.php. To use it specify your arguments in the form:

array(
 '<
long name of argument>' => array(
     'short' => '<
single letter version of argument>',
     'type' => <
'switch' | 'optional' | 'required'>,
     'description' => '<
help text for the argument>',
     'default' => '<
value if this is an optional argument and it isn't specified>',
 ),
 …
 );

There's an example script in the package, and documentation in the readme.txt. The code is freely reusable with no restrictions; I'm just dreaming of a world where no one ever writes another CLI argument parser ever again.

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