Description

Lets you separate algorithms from the objects on which they operate.

Where to use

• Compilers (AST traversal).
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• Exporting data.

Real World Example

You have a graph of shapes. You write an 'XMLExportVisitor' that walks the graph and generates XML, without modifying the shape classes.

Code Example

class Visitor:
    def __init__(self):
        pass

    def execute(self):
        print('Executing Visitor')