[Phpmyadmin-devel] about $common_functions

[Marc Delisle]

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.

-- 
Marc Delisle
http://infomarc.info