[Phpmyadmin-devel] about $common_functions

[Marc Delisle]

Le 2012-07-03 10:44, Rouslan Placella a écrit :
> 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++.

Ok, now I get it. So, let's forget about my suggestion of having a
global variable.

-- 
Marc Delisle
http://infomarc.info