Difference between composer prefer-dist and prefer-source?

Question

Looking at the help for PHP Composer's install command, I see the following two options

$ composer help install Options:  --prefer-source            Forces installation from package sources when possible, including VCS information.  --prefer-dist              Forces installation from package dist even for dev versions. 

What's a "dist" installation? I poked around the composer site and Google but there didn't seem to be anything that addressed this (So I assume it's something core and obvious to folks familiar with Composer — apologies for the newbie question)

I'm assuming --prefer-source is where Composer will ask Packagist for the repository location, and then checkout/clone/export/etc. the project itself.

If so, then where does --prefer-dist download from? What does it download?

Answer 1

According to http://getcomposer.org/doc/03-cli.md, the --prefer-source option will prefer to create a package directory that is a "version control repository". This is equivalent to you typing:

$ git clone ... 

or

$ svn checkout ... 

The --prefer-dist option will prefer to create a non-"version control repository", which is equivalent to you typing:

$ git clone ... ; rm -fr dir/.git 

or

$ svn export ... 

Also, you can define separate repos for source and dist in your composer.json. Here's an example:

{     "repositories": [         {             "type": "package",             "package": {                 "name": "joshuaclayton/blueprint-css",                 "version": "master",                 "source": {                     "url": "git://github.com/joshuaclayton/blueprint-css.git",                     "type": "git",                     "reference": "master",                 }             }         },         {             "type": "package",             "package": {                 "name": "fiftyone/mobi-lite-php",                 "version": "2013.03.06",                 "dist": {                     "url": "http://iweb.dl.sourceforge.net/project/fiftyone/51Degrees.mobi-Lite-2013.03.06.php.zip",                     "type": "zip"                 },             }         }     ] } 

NOTE: for whatever reason, when I use --prefer-dist, I sometimes get errors such as

Fatal error: Cannot redeclare class Zend_Db_Adapter_Pdo_Abstract in ... 

which do not appear when I use --prefer-source. For this reason, I only use --prefer-source, until I figure out the cause of this issue.