Python Trick: Using iter() with a Sentinel for Custom Loops
Most Python developers use iter() to create an iterator from a collection like a list or tuple. However, a lesser-known feature is that you can pass a sentinel (a stopping condition) to iter(), making it a powerful tool for creating custom loops, especially when dealing with streams or file reading.
How It Works: When you pass two arguments to iter(), the first is a callable (like a function), and the second is a sentinel value. The loop will continue to call the function until it returns the sentinel value, which stops the iteration.
Why It’s Cool: Using iter() with a sentinel is a clean and elegant way to handle loops where you need to stop based on a condition without writing manual while loops or adding explicit checks. This trick is particularly useful for reading data from streams, sockets, or files in chunks.
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