Efficiency Yield

Talking to an ex colleague of mine this evening about some use cases for yield, it’s quite a handy little keyword, i often use it for splitting a large collection into smaller ones (Chunk).

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Efficiency

I was presented with another use for yield.

Take a third party API that takes an IEnumerable of objects that are expensive to create,

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we can see that there is an early imageexit strategy so we may not need all items in the enumeration.

 

 

 

 


Now lets say we have 3 implementations of this interfaceimage

trivial i know, but assume we don’t know if they return null or not at compile time.

 

 

Now here’s a nice way of passing all of the above to a third party API and only incur the construction hit as and if when they get enumerated.

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Using the trivial logic outlined here, ExpensiveFactoryC will never get constructed.