Case Statements

[BartC]

On 16/03/2016 12:21, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:

>> That's the first time I've heard a language feature common in C
>> described as sexy.
>
> Scheme has a "switch" statement (a "case" form). However, it is slightly
> better equipped for it than Python:
>
>   * Scheme has an atom type ("symbol"). It corresponds to interned
>     strings and is supposed to be compared by reference.
>
>   * Scheme has defined three equality operators: "eq?", "eqv?" and
>     "equal?". Python only has two: "is" (~ "eq?") and "==" (~ "equal?").
>     The "case" form makes use of the operator "eqv?" that is missing from
>     Python ("eqv?" compares numbers numerically but is otherwise the same
>     as "eq?").
>

Yes, a few scripting languages can do interesting things with switch or 
case statements. Perl for example (where I think it is created out other 
language features, but it looks a regular part of the syntax).

Even Ruby has one. It doesn't do anything 'sexy' with it, but it does 
have this:

  case
  when this
     ....
  when that
     ....
  when other
     ...
  end

which is exactly equivalent to if this... elif that... (when the tests 
are ordered), with one difference:

Each test starts with "when", instead of "if" for the first and "elif" 
for subsequent ones. That makes it easier to reorder tests, temporarily 
comment out the first test, copy a test from elsewhere, insert a new 
first test (you get the idea).

-- 
Bartc