Re: How to use matcharg(2)[1] to set search register?

On Jul 8, 6:44 pm, Gary Johnson <garyj...@spocom.com> wrote:
> On 2012-07-08, Bee wrote:
> > On Jul 8, 3:33 pm, Gary Johnson wrote:
> > > On 2012-06-24, Bee wrote:
> > > > On Jun 24, 10:32 am, Gary Johnson wrote:
> > > > > On 2012-06-24, Bee wrote:
> > > > > > 2match has been set and is working.
>
> > > > > > :echo matcharg(2)[1] returns the correct pattern.
>
> > > > > > Why does this not set the search register?
>
> > > > > > let @/=matcharg(2)[1]
>
> > > > > It works for me.
>
> > > > > Are you setting @/ within a function and expecting that setting to
> > > > > persist after the function returns? That won't work because
> > > > > functions use their own instances of @/.
>
> > > > > Regards,
> > > > > Gary
>
> > > > Thank you, I now see from :help "/
>
> > > > 9. Last search pattern register "/ *quote_/* *quote/*
> > > > ...
> > > > "Note that the valued is restored when returning from a function"
>
> > > > --And--
>
> > > > *function-search-undo*
> > > > The last used search pattern and the redo command "."
> > > > will not be changed by the function. This also
> > > > implies that the effect of |:nohlsearch| is undone
> > > > when the function returns.
>
> > > > BUT...
>
> > > > When the following function exits, the '/' register is still set as it
> > > > was in the function and 'n' will find the next occurance.
> > > > What should it have been restored to?
>
> > > > " toggle match end of long lines
> > > > hi OverLength NONE cterm=underline ctermbg=darkyellow
> > > > function! OverLength(n)
> > > > if matcharg(2)[0] == "OverLength"
> > > > 2match none OverLength
> > > > else "!greater than nth virtual column :help \%>v
> > > > let @/='\%>' . a:n . 'v.*'
> > > > execute '2match OverLength /' . @/ . '/'
> > > > endif
> > > > endf
>
> > > I would expect it to be restored to whatever value it had before the
> > > OverLength() function was called. Are you sure that the '/'
> > > register was not already set to that pattern before the function
> > > was called?
>
> > > If you can do this:
>
> > > 1. :let @/= "hello"
> > > 2. :call OverLength(40)
> > > 3. :echo @/
>
> > > and see that the '/' no longer contains "hello", then you may have
> > > found a bug in Vim.
>
> > > BTW, according to ":help 2match", clearing the match is done with
> > > ":2match none"--the second argument is not needed and appears to be
> > > ignored.
>
> > > Regards,
> > > Gary
>
> > To make it clearer:
>
> > :let @/= "hello"
>
> > :echo @/
> > hello
>
> > :call OverLength(40)
>
> > :echo @/
> > \%>40v.*
>
> > Bill
>
> I just tried that myself, as I suppose I could have earlier, and I
> see the same thing.  I even simplified the function to this:
>
>     function! MyTest()
>       let @/='world'
>     endfunction
>
> and after calling MyTest(), the '/' register contains "world".
>
> However, if I change the function to this:
>
>     function! MyTest()
>       /match
>       echo @/
>     endfunction
>
> and call it, the cursor moves to the next occurrence of "match" in
> the file and the string "match" is echoed to the command line, but
> executing ':echo @/' displays "hello".
>
> So it appears that setting the '/' register indirectly alters a
> local copy, but setting it directly with :let also alters the global
> copy.  I think that's a bug.
>
> The results were the same on versions 7.2.330 and 7.3.584, so it has
> been like this for a while.
>
> Regards,
> Gary

Hi Gary

Will you be writing a bug report?
Or shall I?
Where to post? vim_use or vim_dev

Bill

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