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halayli

Speaking of CPython optimizations

> x = 124236

> y = 124237

> y -= 1

> id(x)

140474467900408

> id(y)

140474467900360

> x is y

False

> x = 1

> y = 2

> y -= 1

> id(x)

140558102245816

> id(y)

140558102245816

> x is y

True

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This is because all integers between -5 and 256 in CPython are "cached", so they all have the same identity (hence the True return value of the `is` of the second comparison -- it's between the range).

http://stackoverflow.com/questions/306313/python-is-operator...

CPython interns ints in [-5, 256]. Seems like a reasonable common-case optimization to me.

Agreed. It didn't surprise me much, but it makes things less consistent.

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