Re: static array declaration in flyweight pattern

=?ISO-8859-1?Q?Marcel_M=FCller?= <>
Sun, 31 May 2009 21:36:19 +0200
<4a22dc36$0$31880$> wrote:

The line Icon *FlyweightFactory::_icons[]; seems a strange definition
of an array. In the class Icon, this array is declared as having
dimension 5 but the definition doesn't specify the size.

This is allowed, since the compiler already knows the size.

The definition of the array also appears to be uninitialized.


particular, I would be interested to know if the static array
declaration ensures that all the int-pointer members of the array are
null pointers. They are either null pointers or uninitialized
pointers but which?

I would probably have written Icon *FlyweightFactory::_icons[] = {0,
0, 0, 0, 0};

While this is possible it introduces an implicit dependency on
MAX_ICONS. If MAX_ICONS is less than 5 you will get a compilation error.
Since POD types are automatically initialized to zero in case of an
incomplete initializer list
   Icon *FlyweightFactory::_icons[] = {0};
would do the job as well.

but it's possible that the code does this anyway.

Not that I have noticed.

Do the int-pointers
initialize to 0 anyway even if this is not made explicit as I did?

No, their values are undefined. But since there is another variable
_numIcons which seems to store the valid part of _icons, this does not
result in undefined behavior.


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