Re: [Boost-users] [fusion] sequence conversion

From: Istvan Buki (buki.istvan_at_[hidden])
Date: 2008-07-20 08:45:04

On Sun, Jul 20, 2008 at 8:41 AM, Zeljko Vrba <zvrba_at_[hidden]> wrote:

> On Sat, Jul 19, 2008 at 06:16:53PM +0200, Istvan Buki wrote:
> >
> > Hi,
> >
> Hi, thanks for the answer!
>
> >
> > I do not know for sure if what I'm working on is a good example for using
> > fusion.
> > It started as an experiment to learn more about some of the boost
> libraries.
> > The application is a very small ETL tool which allows me to load and save
> > data from CSV files or database tables. Each record is represented by a
> > fusion map. Between the load and save components I can insert all kind of
> > filters to transform the data contained in the map.
> >
> This looks like a nice examples, yes.  But why do you use maps instead of
> vectors?
>
>
For example, I use it to implement a join component. It works more or less
like a join between two database table but here the table records are
represented by fusion maps and in each map there is a field used to simulate
the where clause. Using the fusion::at_key<> function on a map makes that
very easy.

It also makes it very easy to filter out a column in a table with the
fusion::erase_key<> function.

Istvan