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Re: How to know if a package is loaded [message #29506 is a reply to message #29503]

Mon, 25 October 2010 10:00

dolik.rce
Messages: 1791
Registered: August 2008
Location: Czech Republic

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luzr wrote on Mon, 25 October 2010 08:37

koldo wrote on Sun, 24 October 2010 16:17

How a cpp source can know if a package is loaded?

Imagine a general purpose library that includes some feature for GridCtrl package. If the programmer uses this package but s/he does not include GridCtrl, there will be a linking error.

Does not it give a nice and simple answer? Smile

BTW, the case described above is a bug of the library - it should have add "GridCtrl" in its 'uses'.

Mirek

We can try to ask once more, being nicer this time Very Happy

Anyway I think what Koldo meant (and me too) is that sometimes it is better to make some extension voluntary. GridCtrl is not the best example, but imagine you would like to provide some extension of the stuff in MySql package - then adding it into your package would make the whole thing unusable on computers which don't have the mysql library installed. But if you could detect if the MySql is already used, than it would be safe to use it. Otherwise, you would just #ifdef out the MySql related parts and everyone would be happy (especially linker Smile

).

Honza

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