Re: Cleaning up iterators

[Petite Abeille <petite.abeille@...>]

On Jul 26, 2011, at 9:10 PM, Antonio Vieiro wrote:

> I'm thinking of using iterator to iterate over the results of a SQL query, something like:
> 
> for row in result("SELECT id,name FROM USER") do
>  if row.id == 3 then break end
> end
> 
> but I need to "clean-up" the iterator when it finishes (i.e. after the loop) or whenever I have a "break" or a "return" statement.
> 
> As far as I understand there's no way to do this, right?

Well, there is always a way, no?

For example, in the first case, the iterator can automatically clause the result set upon exhausting it.   

Say:

local aDB = DB( 'sqlite3://localhost/test.db' )

for aContact in aDB( 'select * from contact' ) do
    print( aContact.name, aContact.email )
end

Otherwise, you could always do it explicitly:

local aCursor = aDB( 'select * from contact' )

for aContact in aCursor do
    print( aContact.name, aContact.email )
    break
end

aCursor.close = true

Implementation details:

http://dev.alt.textdrive.com/browser/HTTP/DB.lua#L194