[ruby-core:56376] [ruby-trunk - Bug #8693] lambda invoked by yield acts as a proc with respect to return

Issue #8693 has been updated by rits (First Last).


mame (Yusuke Endoh) wrote:
> My guess:
> 
> * yield invokes any block as a plain block
> * lambda block always checks the arguments
> 

A "plain block" that "checks arguments" is an oxymoron.  Obviously such a thing should not exist.

If it behaved truly as a plain block that would be saner, however, as long as the lambda is alive (and it is) it still does not make sense for it to run as anything but a lambda.

Incidentally, here's another indication that under the current model, procs passed as blocks are not intended to be decomposed/unpacked into blocks (losing their proc shell in the process), but merely take the block slot as themselves (procs):

irb(main):001:0> l = ->{}
=> #<Proc:0xb9471e90@(irb):1 (lambda)>
irb(main):002:0> proc &l
=> #<Proc:0xb9471e90@(irb):1 (lambda)>

> Anyway, I don't recommend you to write a code that depends on this behavior because this is considered an implementation-detail.
> 
> If you want to use the behavior as a spec, or change the behavior, it would be good to make a feature request with actual use case.
> From my experience, "just making it consistent" is not an effective reason to do it.
> 

The reason for consistency is avoiding surprise and bugs.  If you write a lambda, you expect it to work as a lambda always, as the closest thing to a "spec" we have (ruby programming lang), declares it should.  If it doesn't, that's a guaranteed bug in your code.


----------------------------------------
Bug #8693: lambda invoked by yield acts as a proc with respect to return
https://bugs.ruby-lang.org/issues/8693#change-40888

Author: rits (First Last)
Status: Rejected
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.0.0p247 (2013-06-27) [x64-mingw32]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


irb(main):004:0> def m1; yield end; def m2; m1 &->{return 0}; 1 end; m2
=> 0



-- 
http://bugs.ruby-lang.org/