cvs: pearweb /rfc 003-dependencies.txt

ssb Tue Aug 28 07:14:06 2001 EDT Added files: /pearweb/rfc 003-dependencies.txt Log: * "RFC" document for dependencies Index: pearweb/rfc/003-dependencies.txt +++ pearweb/rfc/003-dependencies.txt Title: Dependencies in PEAR Packages Version: $Revision: 1.1 $ Status: proposal Maintainer: Stig S. Bakken <ssb@fast.no> Created: 2001-08-28 Modified: 2001-08-28 1. Introduction This document describes how PEAR should manage dependencies between packages, or between packages and external components, operating environment and other factors. 2. Dependency Phases There are three phases where dependencies need to be considered: * When a package is built (for packages with C code) * When a package is installed * When a package is used When building a package, there may be dependencies to external libraries, to a certain PHP version or maybe to a specific operating system or web server. If the dependencies in this phase are not satisfied, we'll never get to the next phase. When installing a package, there may also be dependencies to external libraries, especially if it contains a C extension linked with a shared library. The most typical install-time dependencies are to have another package installed, to have a bundled PHP feature enabled or to have a specific or minimum PHP version. Finally there are run-time dependencies. Hopefully everything should be working fine when we get here, but there may be some code that relies on configuration options that may be changed run-time, and the installer has no way of checking that. Run-time dependencies should be handled much more gracefully than build/install-time ones, applying workarounds wherever possible. Php.ini options are typical examples of run-time dependencies: whether the URL fopen wrappers are enabled, whether PHP is running in safe mode, and so on. 3. Dependency Types These are the different types of dependencies we would like to support: * another PEAR package installed * specific version of another PEAR package installed * minimum version of another PEAR package installed * bundled PHP extension available * specific version of PHP with bundled extension available * minimum version of PHP with bundled extension available * specific version of PHP * minimum version of PHP * external program * external library for linking * external runtime library * operating system * specific version of operating system * minimum version of operating system * web server * specific version of web server * minimum version of web server * SAPI backend * specific version of PHP with SAPI backend * minimum version of PHP with SAPI backend