[Phpmyadmin-devel] about $common_functions

[Rouslan Placella]

On 03/07/12 15:42, Marc Delisle wrote:
> Le 2012-07-03 10:11, Rouslan Placella a écrit :
>> On 03/07/12 15:05, Marc Delisle wrote:
>>> Le 2012-07-03 10:00, Rouslan Placella a écrit :
>>>> On 03/07/12 14:51, Marc Delisle wrote:
>>>>> Le 2012-07-03 09:38, Rouslan Placella a écrit :
>>>>>> On 03/07/12 14:34, Marc Delisle wrote:
>>>>>>> Hi,
>>>>>>> I just made a suggestion to Thilina but I want to validate it with
>>>>>>> everyone.
>>>>>>>
>>>>>>> I see a lot of
>>>>>>> $common_functions = PMA_CommonFunctions::getInstance()
>>>>>>>
>>>>>>> inside many functions of the same library. If we know that this library
>>>>>>> is always called from one script, I believe it would be more efficient
>>>>>>> to do this instead, inside the functions:
>>>>>>>
>>>>>>> global $common_functions;
>>>>>>>
>>>>>>> and ensure that $common_functions has been defined in the global scope
>>>>>>> of the calling script.
>>>>>>>
>>>>>>
>>>>>> Doesn't that defeat the purpose of having a singleton class?
>>>>>
>>>>> Well, I don't understand the definition of a singleton. From [0],
>>>>> "the singleton pattern is a design pattern that restricts the
>>>>> instantiation of a class to one object"
>>>>>
>>>>> Does that mean that one such object must exist inside a function, or
>>>>> must exist considering all scopes?
>>>>
>>>> There will be only one in all scopes. However I thought that we were
>>>> trying to reduce the number of globals that we have, since sometimes we
>>>> get problems with undefined globals. Also, if we have a global reference
>>>> to the commonFunctions object, then I see no point in restricting the
>>>> number of instances.
>>>
>>> Ok, so what do you think of this code snippet:
>>>
>>> $query[] = $insert_command . 'INTO '
>>>    . PMA_CommonFunctions::getInstance()->backquote($GLOBALS['db']) . '.'
>>>    . PMA_CommonFunctions::getInstance()->backquote($GLOBALS['table'])
>>>           . ' (' . implode(', ', $query_fields) . ') VALUES ('
>>>           . implode('), (', $value_sets) . ')';
>>>
>>> Does this follow the singleton principle?
>>
>> I don't know about following the principle, but it looks ugly. There
>> should definitely be a local reference to the commonFunctions object.
>>
>> $commonFunctions = PMA_CommonFunctions::getInstance();
>> $query[] = $insert_command . 'INTO '
>>      . $commonFunctions->backquote($GLOBALS['db']) . '.'
>>      . $commonFunctions->backquote($GLOBALS['table'])
>>             . ' (' . implode(', ', $query_fields) . ') VALUES ('
>>             . implode('), (', $value_sets) . ')';
>
> I agree; however, in a previous reply you said "There will be only one
> in all scopes" so I'm confused. Setting $commonFunctions this way in
> each function, has for effect that multiple instances of this kind of
> object will exist in all scopes.
>

The will all be references to the same object. Like pointers in C or C++.