Comment by tialaramex
3 days ago
Which x? There are two in your code, one for each time you introduce a pattern Some(x) and each x has scope which of course ends when that pattern is done with
Notice that the Python doesn't work this way, we didn't make a new variable but instead changed the existing one.
Also, the intent in the Python was a constant, in Rust we'd give this constant an uppercase name by convention, but regardless it's a constant and so of course matching against a constant does what you expect, it can't re-bind a constant, 404 is a constant and so is `const NOT_FOUND: u16 = 404;`
> Which x? There are two in your code, one for each time you introduce a pattern Some(x) and each x has scope which of course ends when that pattern is done with
if each x's scope ends at the end of each case doesn't that mean there's only one x?
> we didn't make a new variable but instead changed the existing one.
so because python doesn't have scopes except for function scopes it shouldn't ever have any new features that intersect with scope?
Also this is pretty much in line for the rest of Python leaving variables around.
The match statement presented is equivalent to an assignment, you do have to know that, but then it's just regular Python.
Being in line with the bad original design decision is another bad design decision, python developers should have a courage to admit these instances to benefit from better decisions in new peps. They didn't do it with pattern matching and now the language has another inferior implementation of a feature that, if implemented correctly, should have had clear block scopes, defined as expressions (as opposed to statements), and disallowed type-diverging branches. Java has designed it right, by the way, despite having a differently behaving switch statement in the language already.
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