On Tue, Aug 11, 2009 at 10:59 AM, dan nessett<dness...@yahoo.com> wrote:
> --- On Mon, 8/10/09, Tim Starling <tstarl...@wikimedia.org> wrote:
>
>> No, the reason is because LocalSettings.php is in the
>> directory
>> pointed to by $IP, so you have to work out what $IP is
>> before you can
>> include it.
>>
>> Web entry points need to locate WebStart.php, and command
>> line scripts
>> need to locate maintenance/commandLine.inc. Then either of
>> those two
>> entry scripts can locate the rest of MediaWiki.
>
> Fair enough, but consider the following.
>
> I did a global search over the phase3 directory and got these hits for the
> string "$IP =" :
>
> .../phase3/config/index.php:30: $IP = dirname( dirname( __FILE__ ) );
> .../phase3/config/index.php:1876: \$IP = MW_INSTALL_PATH;
> .../phase3/config/index.php:1878: \$IP = dirname( __FILE__ );
> .../phase3/includes/WebStart.php:61: $IP = getenv( 'MW_INSTALL_PATH' );
> .../phase3/includes/WebStart.php:63: $IP = realpath( '.' );
> .../phase3/js2/mwEmbed/php/noMediaWikiConfig.php:11: $IP =
> realpath(dirname(__FILE__).'/../');
> .../phase3/LocalSettings.php:17: $IP = MW_INSTALL_PATH;
> .../phase3/LocalSettings.php:19: $IP = dirname( __FILE__ );
> .../phase3/maintenance/language/validate.php:16: $IP = dirname( __FILE__ ) .
> '/../..';
> .../phase3/maintenance/Maintenance.php:336: $IP = strval(
> getenv('MW_INSTALL_PATH') ) !== ''
>
> So, it appears that $IP computation is occurring in 6 files. In addition, $IP
> is adjusted by the relative place of the file in the MW source tree (e.g., in
> validate.php, $IP is set to dirname( __FILE__ ) . '/../..';) Adjusting paths
> according to where a file exists in a source tree is fraught with danger. If
> you ever move the file for some reason, the code breaks.
>
> Why not isolate at least $IP computation in a single function? (Perhaps
> breaking up LocalSettings.php into two parts is overkill, but certainly
> cleaning up $IP computation isn't too radical an idea.) Of course, there is
> the problem of locating the file of the function that does this. One approach
> is to recognize that php.ini already requires potential modification for MW
> use. Specifically, the path to PEAR must occur in 'include_path'. It would be
> a simple matter to add another search directory for locating the
> initialization code.
>
> Or maybe there is a better way of locating MW initialization code. How its
> done is an open issue. I am simply arguing that computing the value of $IP by
> relying on the position of the php file in a source tree is not good software
> architecture. Experience shows that this kind of thing almost always leads to
> bugs.
>
>
>
>
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>
The problem with "putting it in a single function" is you still have
to find where that function is to begin with (I'd assume either
GlobalFunctions or install-utils would define this). At which point
you're back to the original problem: defining $IP yourself so you
can find this.
Yes, we should probably do this all a little more cleanly (at least
one unified style would be nice), but constructing it manually is
pretty much a given for anything trying to find an entry point, as
Tim points out.
-Chad
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