What is "splicing mode" in el-search.el?

What is "splicing mode" in el-search.el?

[Chunyang Xu]

Hello!

I tried el-search.el from gnu elpa and have one problem with it. The
Commentary of el-search.el mentions "splicing mode", but I can't
figure out what it means, can you give me an example?

;; It is possible to replace a match with multiple expressions using
;; "splicing mode".  When it is active, the replacement expression
;; must evaluate to a list, and is spliced instead of inserted into
;; the buffer for any replaced match.

Thanks!

Re: What is "splicing mode" in el-search.el?

[Michael Heerdegen]

Hello Chunyang!

> I tried el-search.el from gnu elpa and have one problem with it.

Great, this is the first remark I got about it :-)  Your comments are
much appreciated, please report every discrepancy you find.  Multi-file
support will come soon, btw.


> The Commentary of el-search.el mentions "splicing mode", but I can't
> figure out what it means, can you give me an example?
>
> ;; It is possible to replace a match with multiple expressions using
> ;; "splicing mode".  When it is active, the replacement expression
> ;; must evaluate to a list, and is spliced instead of inserted into
> ;; the buffer for any replaced match.

It just means that instead of the list, it's elements are inserted into
the buffer, in the same order as in the list.  If you replace e.g. this

    `(f . ,args) -> args

and you have in some buffer

     (f x y)

then this would normally be replaced with

     (x y)

but with splicing mode turned on, you would get

      x y

(Do you have a suggestion for a better name?)

But it seems I have broken this submode with one of my latest commits, I
get an error here when I try to enable it.  Will try to fix soon.


Thanks,

Michael.

Re: What is "splicing mode" in el-search.el?

[Michael Heerdegen]

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Michael Heerdegen <michael_heerdegen@web.de> writes:

> But it seems I have broken this submode with one of my latest commits,
> I get an error here when I try to enable it.  Will try to fix soon.

Here is a quick fix:


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: el-search.patch --]
[-- Type: text/x-diff, Size: 1181 bytes --]

*** /tmp/ediff32294tUJ	2016-09-06 16:55:46.448723416 +0200
--- /home/micha/software/elpa/packages/el-search/el-search.el	2016-09-06 16:54:46.567573946 +0200
***************
*** 647,655 ****
                      (el-search--ensure-sexp-start)
                    (end-of-buffer (goto-char (point-max))))))
              (goto-char 1)
!             (forward-sexp)
              (let ((result (buffer-substring 1 (point))))
!               (if (equal replacement (read result))
                    result
                  (error "Error in `el-search--format-replacement' - please make a bug report"))))
          (kill-buffer orig-buffer)))))
--- 647,655 ----
                      (el-search--ensure-sexp-start)
                    (end-of-buffer (goto-char (point-max))))))
              (goto-char 1)
!             (forward-sexp (if splice (length replacement) 1))
              (let ((result (buffer-substring 1 (point))))
!               (if (equal replacement (read (if splice (format "(%s)" result) result)))
                    result
                  (error "Error in `el-search--format-replacement' - please make a bug report"))))
          (kill-buffer orig-buffer)))))

[-- Attachment #3: Type: text/plain, Size: 20 bytes --]



Thanks,

Michael.

Re: What is "splicing mode" in el-search.el?

[Chunyang Xu]

Hi Michael!

On Tue, Sep 6, 2016 at 10:45 PM, Michael Heerdegen
<michael_heerdegen@web.de> wrote:
> Hello Chunyang!
>
>> I tried el-search.el from gnu elpa and have one problem with it.
>
> Great, this is the first remark I got about it :-)  Your comments are
> much appreciated, please report every discrepancy you find.  Multi-file
> support will come soon, btw.
>
>
>> The Commentary of el-search.el mentions "splicing mode", but I can't
>> figure out what it means, can you give me an example?
>>
>> ;; It is possible to replace a match with multiple expressions using
>> ;; "splicing mode".  When it is active, the replacement expression
>> ;; must evaluate to a list, and is spliced instead of inserted into
>> ;; the buffer for any replaced match.
>
> It just means that instead of the list, it's elements are inserted into
> the buffer, in the same order as in the list.  If you replace e.g. this
>
>     `(f . ,args) -> args
>
> and you have in some buffer
>
>      (f x y)
>
> then this would normally be replaced with
>
>      (x y)
>
> but with splicing mode turned on, you would get
>
>       x y
>

Now I see. After applying your patch, it works like expect.


Thank you very much!

Re: What is "splicing mode" in el-search.el?

[Michael Heerdegen]

Chunyang Xu <xuchunyang.me@gmail.com> writes:

> Now I see. After applying your patch, it works like expect.

Great - thanks for testing.  I've installed the patch in Gnu Elpa.


Regards,

Michael.

Re: What is "splicing mode" in el-search.el?

[tomas]

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On Tue, Sep 06, 2016 at 10:09:15PM +0800, Chunyang Xu wrote:
> Hello!
> 
> I tried el-search.el from gnu elpa and have one problem with it. The
> Commentary of el-search.el mentions "splicing mode", but I can't
> figure out what it means, can you give me an example?
> 
> ;; It is possible to replace a match with multiple expressions using
> ;; "splicing mode".  When it is active, the replacement expression
> ;; must evaluate to a list, and is spliced instead of inserted into
> ;; the buffer for any replaced match.

Since it is for Lisp, I guess it does something similar to `,@' in
macros: i.e. "unwrap" one level of the replacement value, which should
be a list, and insert it in place,

I.e. if the search expression is `foo' and the replacement is (bar baz quux),
you'd get

  (one foo three) -> (one (bar baz quux) three) in non-splicing,

                  -> (one bar baz quux three) in splicing mode.

In macros, this is typically used to insert the whole "body" of
something (e.g. an if, a function def and so on), which isn't
an S-expression but a sequence of things.

But this all is just a guess.

regards
- -- t
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