self

Self: Vim prototype object system

Introduction

Vim Self Object Prototype System allows developer to create object-base scripts (inspired after the David Ungar's Self language).

This code to be used by script developers, not for direct use by end users (by itself, it does nothing).

When Vim version 7.0 with dictionary variables and function references came out, I created this object prototype support script. At that time I was planning to write a text-base windowing system on top of Vim which would allow script to create such things as forms. During script installation having per-script driven forms allowing for the tailoring of the script environment might have been a good thing.

Anyway, time pasted and I moved onto other projects without really finishing this script. Then I wanted to create a Scala language comment generation script much like the jcommenter. Vim script for Java. My first cut, version 1.0, was all imperative: enumerations for the different entity types (class, object, method, etc.); with functions for different behaviors and switch-case statements (i.e., if-elseif-endif) using the enumeration to determine which block of Vim script to execute. This worked but each entity's behavior was scattered throughout the script file.

I then thought to dust off my old object system and re-casting my Scala comment generator using it. While the code size is the same, now behavior is near the data (or in an object's prototype chain).

So, here is the code. Along with this file there are some simple usage example files also in the download. None of the examples, though, are as complex as what is done in the scalacommenter.vim script.

Later, I wanted to enhance Envim to allow one to enter refactoring options. This required some sort of forms capability. Hence, I built {Forms} a Vim library, but, along the way, discovered some bugs in the self code. With this release, I hope they have all been fixed.

Installation

The Self 'self.vim' code file should be in the 'autoload' directory and the 'self.txt' in the 'doc' directory.

Intalling with vim-addon-manager (VAM)

For more information about vim-addon-manager, see vim-addon-manager and Vim-addon-manager getting started

In your .vimrc, add self as shown below:

fun SetupVAM()

  ...

  let g:vim_addon_manager = {}
  let g:vim_addon_manager.plugin_sources = {}

  ....

  let g:vim_addon_manager.plugin_sources['self'] = {'kind': 'git', 'url': 'git://github.com/megaannum/self'}

  let plugins = [
    \ 'self'
    \ ]

  call vam#ActivateAddons(plugins,{'auto_install' : 0})

  ...

endf
call SetupVAM()

Now start Vim. You will be asked by vim-addon-manager if you would like to download and install the self plugin (no dependencies).

Installing with pathogen

I do not use pathogen. An example usage would be welcome.

Usage

A function is created that return a label prototype object.

if g:self#IN_DEVELOPMENT_MODE
  if exists("g:forms#Label")
    unlet g:forms#Label
  endif
endif
function! forms#loadLabelPrototype()
  if !exists("g:forms#Label")
    let g:forms#Label = self#LoadObjectPrototype().clone('forms#Label')
    let g:forms#Label.__text = ''
    ....
  endif
  return g:forms#Label
endfunction

Then, a contructor function is defined that takes a Dictionary of attributes as its parameter, clones the Label prototype object and then initializes with the attributes.

function! forms#newLabel(attrs)
  return forms#loadLabelPrototype().clone().init(a:attrs)
endfunction

Application code would then create a label instance by calling the constructor function.

let attr = {'text': 'Some text'}
let label = forms#newLabel(attr)

In addition, one can clone an existing instance and change the clone's attribute value.

let label_2 = label.clone()
let label_2.__text = 'Some other text'

It is always the case that care must be taken in directly setting an object's attribute because there could be some underlying semantics associated with the value which are being by-passed by directly setting it. The prototype's 'init(attr)' may check those semantics (or there might be a setter method).

Vim

Vim location

Tutorial

There is a self tutorial which can be accessed at Self tutorial and the two example Rational number implementations covered in the tutorial are located at Rational1 and Rational2

Acknowledgements and thanks

• Andy Wokula: provided feedback on help file syntax.