#+TITLE: Perl5 layer

#+TAGS: general|layer|multi-paradigm|programming

[[file:img/perl5.png]]

* Table of Contents                     :TOC_5_gh:noexport:
- [[#description][Description]]
  - [[#features][Features:]]
- [[#install][Install]]
- [[#configuration][Configuration]]
  - [[#choosing-a-backend][Choosing a backend]]
    - [[#company-plsense][Company-plsense]]
      - [[#auto-completion-plsense][Auto-completion: PlSense]]
    - [[#lsp][LSP]]
- [[#key-bindings][Key bindings]]
  - [[#perldoc][Perldoc]]
  - [[#pod-and-here-doc][POD and HERE doc]]
  - [[#find-symbol][Find Symbol]]
  - [[#formatting-code][Formatting Code]]

* Description
This layer adds support for the Perl5 language.

** Features:
- Syntactic and semantic checking using [[https://github.com/flycheck/flycheck][flycheck]]
- Auto-completion
- Format code with =perltidy=
- Jump to symbol definition
- Interactive debug via [[https://github.com/realgud/realgud][realgud]] with [[http://search.cpan.org/~rocky/Devel-Trepan-0.73/lib/Devel/Trepan.pm][trepan.pl]]
- LSP and DAP support

* Install
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =perl5= to the existing =dotspacemacs-configuration-layers= list in this
file.

* Configuration
All layer configurations can be done by setting layer variables in your dotfile.
No custom user config lines are necessary

** Choosing a backend
This layer provides two alternative backends to choose from.

*** Company-plsense
This is the default choice if nothing is set and no lsp layer
is loaded in your dotfile. This mode only provides very
limited IDE capabilities. Used best if only small files
are edited. To set explicitly set the following in your
dotfile:

#+BEGIN_SRC emacs-lisp
  (perl5 :variables perl5-backend 'company-plsense)
#+END_SRC

**** Auto-completion: PlSense
=company-plsense= requires installation of the =plsense= server from [[https://github.com/aki2o/plsense#install][here]].

*** LSP
For proper IDE support this backend should be used. It is
based on an external server which will be started automatically
by emacs, once a perl5 file is opened. The key bindings are
the same for all lsp modes so if you are already familiar with
one you should be able to work the same in all modes.

To set explicitly do the following in your dotfile:

#+BEGIN_SRC emacs-lisp
  (perl5 :variables
         perl5-backend 'lsp)
#+END_SRC

For this to work you will also need to obtain
the latest version of the lsp server from [[https://github.com/richterger/Perl-LanguageServer][here]].

Alternatively the server can be installed with:

#+BEGIN_SRC sh
  cpan Perl::LanguageServer
#+END_SRC

NOTE: Key bindings for LSP are defined in the
LSP layer. Also it is advisable to have a look
at the autocomplete layer for an optimal
intellisense config for LSP.

* Key bindings
** Perldoc
Browse formatted perldocs.

| Key binding | Description                     |
|-------------+---------------------------------|
| ~SPC m h h~ | view perldoc of symbol at point |
| ~SPC m h d~ | view perldoc of any symbol      |

** POD and HERE doc
Select a POD or HERE doc.

| Key binding | Description                            |
|-------------+----------------------------------------|
| ~SPC m v~   | select entire POD or HERE doc at point |

** Find Symbol
Jump to symbol definition.

| Key binding | Description                               |
|-------------+-------------------------------------------|
| ~SPC m g g~ | jump to symbol definition                 |
| ~SPC m g G~ | jump to symbol definition in other window |

** Formatting Code

| Key binding | Description                   |
|-------------+-------------------------------|
| ~SPC m = =~ | format current line or region |
| ~SPC m = b~ | format current buffer         |
| ~SPC m = f~ | format current function       |