In OpenERP first we create custom module and module name is account_demo and then create four file like as __init__.py, __openerp__.py, account_demo.py, account_demo.xml file in your module and create function and function name like accoutss_residual.

The residual amount on a receivable or payable account.move.line will be returned by this function but by default an amount in the currency of this journal will be returned by it.

And than when later on if you passed 'residual_in_company_currency' = True in the context then the returned amount will be in company currency.

Using this code given below

 def accoutss_residual(self, cr, uid, ids, field_names, args, context=None):

        res = {}
        if context is None:
            context = {}
        cur_obj = self.pool.get('res.currency')
        for move_line in self.browse(cr, uid, ids, context=context):
            res[move_line.id] = {
                'amount_residual': 0.0,
                'amount_residual_currency': 0.0,
            }
            if move_line.reconcile_id:
                continue
            if not move_line.account_id.reconcile:
                continue
            if move_line.currency_id:
                move_line_total = move_line.amount_currency
                sign = move_line.amount_currency < 0 and -1 or 1
            else:
                move_line_total = move_line.debit - move_line.credit
                sign = (move_line.debit - move_line.credit) < 0 and -1 or 1
            line_total_in_company_currency =  move_line.debit - move_line.credit
            context_unreconciled = context.copy()
            if move_line.reconcile_partial_id:
                for payment_line in move_line.reconcile_partial_id.line_partial_ids:
                    if payment_line.id == move_line.id:
                        continue
                    if payment_line.currency_id and move_line.currency_id and payment_line.currency_id.id == move_line.currency_id.id:
                            move_line_total += payment_line.amount_currency
                    else:
                        if move_line.currency_id:
                            context_unreconciled.update({'date': payment_line.date})
                            amount_in_foreign_currency = cur_obj.compute(cr, uid, move_line.company_id.currency_id.id, move_line.currency_id.id, (payment_line.debit - payment_line.credit), round=False, context=context_unreconciled)
                            move_line_total += amount_in_foreign_currency
                        else:
                            move_line_total += (payment_line.debit - payment_line.credit)
                    line_total_in_company_currency += (payment_line.debit - payment_line.credit)

            result = round(move_line_total)
            res[move_line.id]['amount_residual_currency'] =  sign * (move_line.currency_id and self.pool.get('res.currency').round(cr, uid, move_line.currency_id, result) or result)
            res[move_line.id]['amount_residual'] = sign * line_total_in_company_currency
        return res