How to prevent smartparens slurp from slurping item separator?

Question

I am looking into Erlang support for smartparens and would like to be able to slurp a string into the current list without including the Erlang statement termination colon in the list.

In an erlang-mode buffer, with point identified as ∎, if I start with:

Name = ∎"Joe".

and then type [ which is paired so I get:

Name = [∎]"Joe".

If I then execute sp-forward-slurp-sexp, the result is:

Name = [∎"Joe".]

What would be the standard way to update smartparens support to end up instead with the following?:

Name = [∎"Joe"].

PRouleau · Accepted Answer · 2021-10-07T13:51:45.847

I found out that smartparens has a similar command that has slightly different behaviour and works better with Erlang or languages that use separators like C. The command is sp-slurp-hybrid-sexp.

With it I get the result I wanted:

Name = [∎"Joe"].

Unfortunately neither command work perfectly to slurp items and handle separator in all cases. Slurping from [1,2,3], 4, 5 may end up with [1,2,3 4], 5 or [1,2,3 4],,5. I assume that more work is required to properly support Erlang and some extra learning of the implementation logic is required.

Update - To properly fix the issue : use a function that fix the block:

My final solution to this problem was to write a function that checks the validity of the comma separated block and fix it if it's invalid. Then add that function as a post handler for Erlang operation.

The function I wrote for this is pel-syntax-fix-block-content, available in this answer.

The I wrote the following and my init calls pel-smartparens-setup-erlang when smartparens cod in an erlang-mode buffer:

(defun pel-sp-erlang-handler (_id action _context)
  "Check validity of block and fix it if it was broken by smartparens.                                                                                                                         
                                                                                                                                                                                               
This is a smartparens post-handler and receives 3 arguments:                                                                                                                                   
ID, ACTION and CONTEXT."                                                                                                                                                     
  (when (memq action '(slurp-forward
                       barf-forward
                       split-sexp))
    (pel-syntax-fix-block-content (- (point) 2))
    (forward-char 2)))

                                                                                                                                                                               
(defun pel-smartparens-setup-erlang ()
  "Configure smartparens for Erlang.                                                                                                                                                           
                                                                                                                                                                                               
This must be called within the scope of a erlang-mode buffer."
  (sp-local-pair 'erlang-mode "(" ")"
                 :actions '(insert wrap autoskip navigate)
                 :post-handlers '(pel-sp-erlang-handler))
  (sp-local-pair 'erlang-mode "[" "]"
                 :actions '(insert wrap autoskip navigate)
                 :post-handlers '(pel-sp-erlang-handler))
  (sp-local-pair 'erlang-mode "{" "}"
                 :actions '(insert wrap autoskip navigate)
                 :post-handlers '(pel-sp-erlang-handler))
  (sp-local-pair 'erlang-mode "<<" ">>"
                 :actions '(insert wrap autoskip navigate)
                 :post-handlers '(pel-sp-erlang-handler)))

How to prevent smartparens slurp from slurping item separator?

1 Answers1