PHP Objects, Patterns and Practice (3rd edition)

CHAPTER 15 ■ AN INTRODUCTION TO PEAR AND PYRUS

Table 15–3. package.xml Dependency Types

Element Description

php The PHP application

package A PEAR package

extension A PHP extension (a capability compiled into PHP such as zlib or GD)

arch Operating system and processor architecture

os An operating system

Up until now I have specified mandatory dependencies. In fact, after requires, you can specify an
optional element. This accepts the same dependency elements. When PEAR encounters an unfilled
optional dependency, it will raise a warning but will continue to install nonetheless. You should add
depencies to the optional element where your package can limp along adequately without the preferred
package or extension.
If the user runs the pear install command with the -o flag

pear install -o package.xml

then PEAR will attempt to download and install all unmet required dependencies (remember, though
that passing -o to pyrus means that it will install optional requrements). Running the command with the
-a flag also automates the download of dependencies but will take in optional as well as required
packages.

Tweaking Installation with phprelease

Although you define the files in a package archive with the contents element, you can use phprelease to
fine tune the files that are actually installed onto the users system. Here are the two phprelease elements
in our package: