Thanks Joaquín, Will try modify & the reasons I am wrapping the map class with a another one is to make sure that the users of the class just get access to APIs and not to the container as such & and also each key is used by a different classes to do lookups. Hence two unique keys. Thanks for your response. Regards Ramesh On Tue, Aug 12, 2008 at 11:31 AM, JOAQUIN M. LOPEZ MUÑOZ <joaquin@tid.es>wrote:

Hi Ramesh,

------------------------------ *De:* boost-users-bounces@lists.boost.org [ boost-users-bounces@lists.boost.org] En nombre de Ramesh [ rramesh1@gmail.com] *Enviado el:* martes, 12 de agosto de 2008 7:40 *Para:* boost-users@lists.boost.org *Asunto:* [Boost-users] Multi-index container (Modifying non-unique key in the container)

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Hi.

I am using boost multi-index container for storing objects of type class

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Key 3 are unique and key2 is non-unique. I try to insert objects of type A and it works fine. No issues.

At some point after the insertion, I wish to modify the key2 to 20 in

A, in the class key1 & the container. Can I do this

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with modify? If yes How do I define the iterator (since I need to do a find based on key1 but modify key2 in the container)

You have two options:

1. Use modify(), which is passed the entire element rather than the key, and modify key2 at your pleasure. 2. Project the key1-iterator to a key2-iterator using the projection facilities:

http://www.boost.org/libs/multi_index/doc/tutorial/basics.html#projection

and then use modify_key() with the key2-iterator.

BTW, I've noticed that you're wrapping the A objects into a DataMap class that, oddily enough, replicates the key1, key2 and key3 members. Why aren't you using A members directly thus disposing of the DataMap wrapper?

Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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