[TYPO3-core] RFC #10454: t3lib_div::makeInstanceClassName() allows to bypass checks for t3lib_Singleton

[Ingo Renner]

Hi all,

This is a SVN patch request

Type: feature

Branches: trunk

BT reference: http://bugs.typo3.org/view.php?id=10454

Problem:
When marking a class as singleton by implementing t3lib_Singleton one 
can assure that at any time there's only one instance of that class when 
consistently using t3lib_div::makeInstance(). However, one can 
circumvent this and still create multiple instances of the class by 
using t3lib_div::makeInstanceClassName() together with the new operator.

The same problem arises when implementing t3lib_Singleton and requiring 
arguments to be passed to the constructor of that class. This class can 
only be instanciated by using t3lib_div::makeInstanceClassName() and the 
new operator, and thus again bypassing the check for the singleton.

This can have multiple implications with performance and also behavior.


Solution:
* make t3lib_div::makeInstance() aware of constructor arguments in the 
first step.
* make the functionality of t3lib_div::makeInstanceClassName() available 
as a protected internal function. This functionality is still needed to 
recursively resolve xclassed class names.
* mark t3lib_div::makeInstanceClassName() as deprecated with a hint for 
t3lib_div::makeInstance()
* replace all occurances of t3lib_div::makeInstanceClassName() in the 
core with t3lib_div::makeInstance() calls. (separate issue)
* later, with TYPO3 4.5, remove t3lib_div::makeInstanceClassName() 
eventually enforcing the check for singletons


How to reproduce:
The last hunk in the patch acts as an example of how the code is cleaned 
up and still works. This hunk is not "part" of the actual patch and is 
not intended for the commit with this issue.


Notes:
We can of course not prevent someone from directly using the new 
operator with the class name, but this is out of scope for this issue as 
it's considered unclean anyways as xclasses aren't taken into account 
this way.

With this patch you can finally do this: 
t3lib_div::makeInstance('myClass', $arg1, $arg2,  ..., $argN);



all the best
Ingo

-- 
Ingo Renner
TYPO3 Core Developer, Release Manager TYPO3 4.2

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