Method _construct

lib/sqlalchemy/sql/elements.py:3347–3405

(
        cls,
        operator: OperatorType,
        continue_on: Any,
        skip_on: Any,
        initial_clause: Any = _NoArg.NO_ARG,
        *clauses: Any,
        **kw: Any,
    )

    @classmethod
    def _construct(
        cls,
        operator: OperatorType,
        continue_on: Any,
        skip_on: Any,
        initial_clause: Any = _NoArg.NO_ARG,
        *clauses: Any,
        **kw: Any,
    ) -> ColumnElement[Any]:
        if initial_clause is _NoArg.NO_ARG:
            # no elements period.  deprecated use case.  return an empty
            # ClauseList construct that generates nothing unless it has
            # elements added to it.
            name = operator.__name__

            util.warn_deprecated(
                f"Invoking {name}() without arguments is deprecated, and "
                f"will be disallowed in a future release.   For an empty "
                f"""{name}() construct, use '{name}({
                    'true()' if continue_on is True_._singleton else 'false()'
                }, *args)' """
                f"""or '{name}({
                    'True' if continue_on is True_._singleton else 'False'
                }, *args)'.""",
                version="1.4",
            )
            return cls._construct_raw(operator)

        lcc, convert_clauses = cls._process_clauses_for_boolean(
            operator,
            continue_on,
            skip_on,
            [
                coercions.expect(roles.WhereHavingRole, clause)
                for clause in util.coerce_generator_arg(
                    (initial_clause,) + clauses
                )
            ],
        )

        if lcc > 1:
            # multiple elements.  Return regular BooleanClauseList
            # which will link elements against the operator.

            flattened_clauses = itertools.chain.from_iterable(
                (
                    (c for c in to_flat._flattened_operator_clauses)
                    if getattr(to_flat, "operator", None) is operator
                    else (to_flat,)
                )
                for to_flat in convert_clauses
            )

            return cls._construct_raw(operator, flattened_clauses)  # type: ignore # noqa: E501
        else:
            assert lcc
            # just one element.  return it as a single boolean element,
            # not a list and discard the operator.