Delegating Generators with yield from

1Concept

`yield from <iterable>` delegates generator execution to a sub-generator. It flattens nested iterables and transparently establishes a two-way communication channel passing `.send()` and `.throw()` between the caller and sub-generator.

2Architecture Diagram

Outer Generator ---> yield from Sub-Generator ---> Directly Streams Values to Client

3Code Example

def sub_task(prefix: str, count: int):
    for i in range(1, count + 1):
        yield f"{prefix}-{i}"

def master_pipeline():
    yield from sub_task("Ingest", 2)
    yield from sub_task("Transform", 2)
    yield from sub_task("Export", 1)

print(f"Pipeline stages: {list(master_pipeline())}")

4Expected Output

Pipeline stages: ['Ingest-1', 'Ingest-2', 'Transform-1', 'Transform-2', 'Export-1']

5Key Takeaways

• ✓`yield from` replaces verbose nested loops (`for x in subgen: yield x`).
• ✓Establishes a bi-directional data channel between delegating caller and sub-generators.
• ✓The return value of the sub-generator (`return val`) becomes the value of the `yield from` expression.