Comment by tialaramex

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;`

almostgotcaught 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

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?

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Spivak 3 days ago
Also this is pretty much in line for the rest of Python leaving variables around.
for x in [1]: pass print(x) # => 1
The match statement presented is equivalent to an assignment, you do have to know that, but then it's just regular Python.
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- instig007 3 days ago
  
  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.
  
  Reply View | 4 replies
  
  lou1306 3 days ago
  
  > Being in line with the bad original design decision is another bad design decision
  I disagree. Consistently going with the "bad" choice (in this case, leaking the variable to the outer scope) is better inconsistently swinging between 2 ways of doing things. Least astonishment!
  
  Reply View | 3 replies