# dbh_stack

#    Used by &set_dbh and &restore_dbh to hold other database

#    handles for this context.

This database handle is cached for future use: if you call

C<C4::Context-E<gt>dbh> twice, you will get the same handle both

times. If you need a second database handle, use C<&new_dbh> and

possibly C<&set_dbh>.

#'

=head2 set_dbh

  $my_dbh = C4::Connect->new_dbh;

  C4::Connect->set_dbh($my_dbh);

  ...

  C4::Connect->restore_dbh;

C<&set_dbh> saves the current database handle on a stack, then sets

the current database handle to C<$my_dbh>.

C<$my_dbh> is assumed to be a good database handle.

=cut

#'

sub set_dbh

{

    my $self = shift;

    my $new_dbh = shift;

    # Save the current database handle on the handle stack.

    # We assume that $new_dbh is all good: if the caller wants to

    # screw himself by passing an invalid handle, that's fine by

    # us.

    push @{$context->{"dbh_stack"}}, $context->{"dbh"};

    $context->{"dbh"} = $new_dbh;

}

=head2 restore_dbh

  C4::Context->restore_dbh;

Restores the database handle saved by an earlier call to

C<C4::Context-E<gt>set_dbh>.

=cut

#'

sub restore_dbh

{

    my $self = shift;

    if ($#{$context->{"dbh_stack"}} < 0)

    {

        # Stack underflow

        die "DBH stack underflow";

    }

    # Pop the old database handle and set it.

    $context->{"dbh"} = pop @{$context->{"dbh_stack"}};

}

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