HiveBrain v1.2.0
Get Started
← Back to all entries
patternMinor

Accessor functions in elisp

Submitted by: @import:stackexchange-codereview··
0
Viewed 0 times
functionselispaccessor

Problem

I'm writing some simple emacs tools for visual studio solutions.

I've got a function sln-process-csproj-file. This function takes the path to a project, and returns a tuple that's just a data model of the innards of the project.

Right now the return value on the last line of that function is `(,project-name ,project-path ,project-files).

I have written three getter functions to use with the list:

(defun sln-project-name (project)
  (nth 0 project))

(defun sln-project-path (project)
  (nth 1 project))

(defun sln-project-files (project)
  (nth 2 project))


Does this getter and setter boilerplate code match best practices? Is there a shorter way to write it?

Solution

Yes, it can be shortened by using defstruct. An example from the docs:

(cl-defstruct person name age sex)
      (setq dave (make-person :name "Dave" :sex 'male))
           ⇒ [cl-struct-person "Dave" nil male]
      (setq other (copy-person dave))
           ⇒ [cl-struct-person "Dave" nil male]
      (eq dave other)
           ⇒ nil
      (eq (person-name dave) (person-name other))
           ⇒ t
      (person-p dave)
           ⇒ t
      (person-p [1 2 3 4])
           ⇒ nil
      (person-p "Bogus")
           ⇒ nil
      (person-p '[cl-struct-person counterfeit person object])
           ⇒ t


Alternatively, if you want something more heavy weight, there is a CLOS-like object system.

Code Snippets

(cl-defstruct person name age sex)
      (setq dave (make-person :name "Dave" :sex 'male))
           ⇒ [cl-struct-person "Dave" nil male]
      (setq other (copy-person dave))
           ⇒ [cl-struct-person "Dave" nil male]
      (eq dave other)
           ⇒ nil
      (eq (person-name dave) (person-name other))
           ⇒ t
      (person-p dave)
           ⇒ t
      (person-p [1 2 3 4])
           ⇒ nil
      (person-p "Bogus")
           ⇒ nil
      (person-p '[cl-struct-person counterfeit person object])
           ⇒ t

Context

StackExchange Code Review Q#42086, answer score: 8

Revisions (0)

No revisions yet.