With statement

[jprochazk]

with_stmt := 'with' (var ':=')? expr ':' block

import file.open

with f := open("file.txt").append():
  for i in 0..100:
    f.write(str(i))

Semantics

1. A new scope is opened
2. An anonymous binding temp is created
3. The expr is evaluated, and stored in temp
4. The var binding is created
5. temp is copied to var
6. The enter metamethod is called on the value stored in temp
7. The block is executed
8. The leave metamethod is called on teh value stored in temp
9. The scope is closed

A possible desugaring would look like:

temp := <expr>
var := temp
temp.enter()
<block>
temp.leave()