[TYPO3-core] RFC #15075: feature: make a pre-check for required php-extensions

[Xavier Perseguers]

Hi Jigal,

Finally found time to review your patch.

>> Unfortunately the discussion about separating this module list to
>> required and alternative modules (mysql) is not in the patch. IMHO we
>> agreed on this separation, didn't we?
>> I am still waiting for it before voting.
>
> The request by Xavier was to make it possible to have "required" modules
> and "one of this set is required" modules.
> This is done by having an array of:
> - module names (each module is required)
> - sub-arrays of module names (at least one of this set is required)
>
> So what's missing in your opinion? :-)

That's OK for me.

>> The patch in this form looks like adding a feature which obviously
>> introduces new bugs. I do not like that, since we are not in a hurry.
>
> That's a rather pessimistic view on the world ;-)
> What kind of bugs do you predict to come from this check?
>
> It's nothing more or less than a quick test for PHP modules which are
> required to run TYPO3. It's only done in the 123 installer to catch
> these problems in an early stage. Instead of ugly fatal PHP errors
> you'll see a simple but decent error message stating which PHP modules
> are needed to install (or run) TYPO3.

I did not test it with DBAL, just read it and it won't work as DBAL does 
not XCLASS the installer (we used a hook-like construction to avoid this 
paradigm).

There's two problems:

1) Test for required modules is being done before DBAL has a chance to 
hook in (around lines 261-273) while autoloader of DBAL is included 
around lines 343-347
2) DBAL makes use of hooks to integrate within installer:

	// Hook to override and add steps to the 1-2-3 installer
if (is_array 
($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/install/mod/class.tx_install.php']['stepOutput'])) 
{
	foreach 
($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/install/mod/class.tx_install.php']['stepOutput'] 
as $classData) {
		$hookObject = t3lib_div::getUserObj($classData);
		$hookObject->executeStepOutput($markers, $this->step, $this);
	}
}

=> DBAL should have a chance to autoload before your test
=> Your getMissingPHPModules() method should provide a hook that DBAL 
would use to override the list of modules

Besides that, reading review:

- use "protected" instead of "var" for member declaration. Var is a 
keyword from PHP4, starting from PHP5 we should have proper visibility 
keyword (private/protected/public) even if old members still have the 
"var" declaration

Thanks for your work!

Xavier