sqlalchemy.sql.visitors.ReplacingExternalTraversal

class documentation

class ReplacingExternalTraversal(CloningExternalTraversal):

Known subclasses: sqlalchemy.sql.util.ClauseAdapter

Base class for visitor objects which can traverse using the .visitors.replacement_traverse function.

Direct usage of the .visitors.replacement_traverse function is usually preferred.

Method	`replace`	Receive pre-copied elements during a cloning traversal.
Method	`traverse`	Traverse and visit the given expression structure.

Inherited from CloningExternalTraversal:

Method copy_and_process Apply cloned traversal to the given list of elements, and return the new list.

Inherited from ExternalTraversal (via CloningExternalTraversal):

Method	`chain`	'Chain' an additional ClauseVisitor onto this ClauseVisitor.
Method	`iterate`	Traverse the given expression structure, returning an iterator of all elements.
Method	`traverse_single`	Undocumented
Class Variable	`__traverse_options__`	Undocumented
Property	`_visitor_dict`	Undocumented
Property	`visitor_iterator`	Iterate through this visitor and each 'chained' visitor.

def replace(self, elem):

overridden in sqlalchemy.sql.util.ClauseAdapter

Receive pre-copied elements during a cloning traversal.

If the method returns a new element, the element is used instead of creating a simple copy of the element. Traversal will halt on the newly returned element if it is re-encountered.

def traverse(self, obj):

overrides sqlalchemy.sql.visitors.CloningExternalTraversal.traverse

overridden in sqlalchemy.sql.util.ColumnAdapter

Traverse and visit the given expression structure.