expression.py 文件源码

def __init__(self, keyword, *selects, **kwargs):
        self._auto_correlate = kwargs.pop('correlate', False)
        self.keyword = keyword
        self.selects = []

        numcols = None

        # some DBs do not like ORDER BY in the inner queries of a UNION, etc.
        for n, s in enumerate(selects):
            s = _clause_element_as_expr(s)

            if not numcols:
                numcols = len(s.c)
            elif len(s.c) != numcols:
                raise exc.ArgumentError('All selectables passed to '
                        'CompoundSelect must have identical numbers of '
                        'columns; select #%d has %d columns, select '
                        '#%d has %d' % (1, len(self.selects[0].c), n
                        + 1, len(s.c)))

            self.selects.append(s.self_group(self))

        SelectBase.__init__(self, **kwargs)