Blocks, procs && lambdas
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This document summarizes closures and different closure types in Ruby including blocks, procs, and lambdas. Blocks are not objects but can be passed explicitly. Procs are method objects that can be called and passed arguments. Lambdas are similar to procs but check the number of arguments and treat return like break.
![Closure (CS)
● function or reference to a function together
with a referencing environment
● closure <..> allows a function to access
those non-local variables even when invoked
outside of its immediate lexical scope [1]
1 - http://en.wikipedia.org/wiki/Closure_%28computer_science%29](https://image.slidesharecdn.com/blocksprocslambdas-130514015512-phpapp01/85/Blocks-procs-lambdas-2-320.jpg)
Blocks, procs && lambdas
- 1. Blocks, procs && lambdas #16 ruby workshop, 2013-03-24 Vidmantas Kabošis
- 2. Closure (CS) ● function or reference to a function together with a referencing environment ● closure <..> allows a function to access those non-local variables even when invoked outside of its immediate lexical scope [1] 1 - http://en.wikipedia.org/wiki/Closure_%28computer_science%29
- 3. Closures in Ruby 1. Block 2. Proc 3. proc 4. lambda
- 4. Blocks ● NOT an object (mind=blown) ● Implicit pass/call ● Explicit pass/call* ● Speed! Explicit invoke is considerably slower (~50%)* ● Implicit block within implicit block? ● Implicit block behaves like Proc*
- 5. Proc ● Pretty usual method object ● Call ● Pass any number of argument(s) ● respond_to(:arity) ● Flow control keywords (return, break, redo, retry, ...)
- 6. proc ● Ruby 1.8: proc == lambda ● Ruby 1.9 and up: proc == Proc ○ lambda?
- 7. lambda ● Count of arguments ● return == break (proc) ● ->
- 8. end ● Implicit blocks are not objects, but can become an object when referenced (explicitly) ● Proc.new == proc, don't care about args too much & returns ● lambda counts args & diminutive returns
- 9. end!