Closures/Value capture: Difference between revisions
Content added Content deleted
(Added Racket) |
|||
| Line 810: | Line 810: | ||
=={{header|Ruby}}== |
=={{header|Ruby}}== |
||
<lang ruby> |
<lang ruby>list = {} |
||
(1..10).each {|i| list[i] = proc {i * i}} |
|||
=> 1..10 |
|||
p list[3].call #=> 9 |
|||
p list[7][] #=> 49 |
|||
=> 9 |
|||
i = 5 |
|||
irb(main):003:0> list[7][] |
|||
=> |
p list[3].call #=> 9</lang> |
||
This works because ''i'' in <code>(1..10).each {|i| ...}</code> is local to its block. The loop calls the block 10 times, so there are 10 different variables to capture. |
This works because ''i'' in <code>(1..10).each {|i| ...}</code> is local to its block. The loop calls the block 10 times, so there are 10 different variables to capture. |
||
| Line 822: | Line 822: | ||
However, (on both Ruby 1.8 and 1.9) when using a for loop, the loop variable is shared and not local to each iteration: |
However, (on both Ruby 1.8 and 1.9) when using a for loop, the loop variable is shared and not local to each iteration: |
||
<lang ruby> |
<lang ruby>list = {} |
||
for i in 1..10 do list[i] = proc {i * i} end |
|||
=> 1..10 |
|||
p list[3][] #=> 100 |
|||
i = 5 |
|||
=> 100</lang> |
|||
p list[3][] #=> 25</lang> |
|||
=={{header|Scheme}}== |
=={{header|Scheme}}== |
||