Hi Bram,
2016/7/31 Sun 4:17:46 UTC+9 Bram Moolenaar wrote:
> Ken Takata wrote:
>
> > 2016/7/30 Sat 5:38:42 UTC+9 Bram Moolenaar wrote:
> > > Patch 7.4.2120
> > > Problem: User defined functions can't be a closure.
> > > Solution: Add the "closure" argument. Allow using :unlet on a bound
> > > variable. (Yasuhiro Matsumoto, Ken Takata)
> > > Files: runtime/doc/eval.txt, src/testdir/test_lambda.vim,
> > > src/userfunc.c,
> > > src/eval.c src/proto/userfunc.pro
> >
> > I had a report that this patch doesn't work as expected:
> >
> > function! Foo()
> > let x = 0
> > function! Bar() closure
> > let x += 1
> > return x
> > endfunction
> > return function('Bar')
> > endfunction
> >
> > let Count = Foo()
> > echo Count() " => 1
> > echo Count() " => 2
> > echo Count() " => 3
> >
> > let Count2 = Foo()
> > echo Count() " => 1 (Should be 4)
I found another problem. The following causes an error:
function! Foo()
let x = 0
function! Bar() closure
let x += 1
return x
endfunction
return function('Bar')
endfunction
let Count = Foo()
call test_garbagecollect_now()
echo Count() " Cannot access x
Reference counting was wrong. The following patch fixes the problem:
https://bitbucket.org/k_takata/vim-ktakata-mq/src/7685fd93bf6a1ea0079d7c7da537dc062a67bc9f/fix-closure-refcount.patch?at=default
> Calling Foo() creates a new context in which "x" is set to zero.
> And a new Bar() is created that uses this "x". It should not re-use the
> existing Bar(), it is still in use, being referenced.
>
> Thus where it says: /* redefine existing function */
> It should leave that function alone and create a new one. But the new
> Bar() must be the one that's found in the global scope. Thus it's a mix
> of defining a new function and replacing an existing one.
Hmm, do you say that this is expected behavior?
I think Bar() should be an unnamed function like a lambda, and it should not
overwrite existing Bar(). Bar() should be a local function inside Foo().
I wrote a patch to fix this:
https://bitbucket.org/k_takata/vim-ktakata-mq/src/7685fd93bf6a1ea0079d7c7da537dc062a67bc9f/fix-closure.patch?at=default
Please apply the following patch before the above patch:
https://groups.google.com/d/msg/vim_dev/xSCXQ0cmnzo/UUfR81o0BgAJ
fix-closure-refcount.patch is also needed.
With these patches, "function! Bar() closure" creates an unnamed function
(internal name: "<closure>N"), and set the Funcref to a local variable "Bar".
This is a little bit tricky by the counter example works fine.
What do you think?
Regards,
Ken Takata
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