Comments plugin: Switch to using the list field to attach comments

https://github.com/Jermolene/TiddlyWiki5/issues/3378#issuecomment-413137626

plugins/tiddlywiki/comments/add-comment-button-actions.tid

@@ -1,5 +1,7 @@
 title: $:/plugins/tiddlywiki/comments/add-comment-button-actions
 
 <$set name="username" value={{$:/status/UserName}} emptyValue="(anonymous)">
-<$action-createtiddler $basetitle={{{ [[Comment by ']addsuffix<username>addsuffix[' on ']addsuffix<currentTiddler>addsuffix[']] }}} comment-target=<<currentTiddler>> text="" edit-mode="yes"/>
+<$set name="target" filter="[<currentTiddler>]">
+<$action-createtiddler $basetitle={{{ [[Comment by ']addsuffix<username>addsuffix[' on ']addsuffix<currentTiddler>addsuffix[']] }}} role="comment" list=<<target>> text="" edit-mode="yes"/>
+</$set>
 </$set>

plugins/tiddlywiki/comments/comments-template.tid

@@ -2,7 +2,7 @@ title: $:/plugins/tiddlywiki/comments/comments-template
 
 <div class="tc-comments">
 <ol class="tc-comment-list">
-<$list filter="[all[tiddlers+shadows]comment-target<currentTiddler>sort[created]!has[draft.of]]">
+<$list filter="[all[tiddlers+shadows]role[comment]contains<currentTiddler>sort[created]!has[draft.of]]">
 <li>
 <div class="tc-comment-entry">
 <div class="tc-comment-entry-heading">

plugins/tiddlywiki/comments/filter-all-comments.tid

@@ -1,5 +1,5 @@
 title: $:/plugins/tiddlywiki/comments/filter-all-comments
 tags: $:/tags/Filter
-filter: [has[comment-target]!sort[modified]]
+filter: [role[comment]!sort[modified]]
 description: All comments
 

plugins/tiddlywiki/comments/header-view-template-segment.tid

@@ -2,8 +2,15 @@ title: $:/plugins/tiddlywiki/comments/header-view-template-segment
 tags: $:/tags/ViewTemplate
 list-before: $:/core/ui/ViewTemplate/body
 
-<$list filter="[all[current]has[comment-target]]" variable="ignore">
+<$list filter="[all[current]role[comment]]" variable="ignore">
 <div class="tc-is-comment-header">
-This tiddler is a comment on <$link to={{!!comment-target}}><$text text={{!!comment-target}}/></$link>
+This tiddler is a comment on:
+<ul>
+<$list filter="[list<currentTiddler>sort[title]]">
+<li>
+<$link to=<<currentTiddler>>><$text text=<<currentTiddler>>/></$link>
+</li>
+</$list>
+</ul>
 </div>
 </$list>

plugins/tiddlywiki/comments/readme.tid

@@ -9,3 +9,15 @@ This plugin provides a simple means for adding threaded comments to tiddlers.
 * By default, comments are available on all non-system tiddlers. The ''config'' tab lets you customise which tiddlers can accept comments by specifying a filter extension
 * The buttons for adding and editing comments are only available if the system tiddler [[$:/status/IsReadOnly]] is not set to `yes`
 * Use the "All comments" option in the $:/AdvancedSearch ''Filter'' tab to see or export all comments
+
+!! Data Model
+
+The data model employed by the comments plugin is very simple:
+
+* Comment tiddlers are identified by the `role` field being set to `comment`
+* The `list` field of comment tiddlers lists the tiddlers to which this comment applies
+** It is thus possible for a comment to be applied to multiple tiddlers at once
+** The links between comments can be preserved when renaming them by using the relink checkbox in the edit template
+* The `edit-mode` field of comment tiddlers is set to `yes` to display it in edit mode, or `no` to display it in view mode
+* The `saved-text` field is updated when switching to edit mode so that it can be restored if the user cancels
+

plugins/tiddlywiki/comments/sidebar.tid

@@ -3,12 +3,15 @@ tags: $:/tags/SideBar
 caption: Comments
 
 <div class="tc-timeline">
-<$list filter="[all[tiddlers+shadows]has[comment-target]has[modified]!sort[modified]eachday[modified]]">
+<$list filter="[all[tiddlers+shadows]role[comment]has[modified]!sort[modified]eachday[modified]]">
 <div class="tc-menu-list-item">
 <$view field="modified" format="date" template="DDth MMM YYYY"/>
-<$list filter="[all[tiddlers+shadows]has[comment-target]sameday:modified{!!modified}!sort[modified]]">
+<$list filter="[all[tiddlers+shadows]role[comment]sameday:modified{!!modified}!sort[modified]]">
 <div class="tc-menu-list-subitem">
-<$link>Comment by '<$view field="modifier">(anonymous)</$view>' on <$text text={{!!comment-target}}/></$link>
+<$link>Comment by '<$view field="modifier">(anonymous)</$view>'</$link> on
+<$list filter="[list<currentTiddler>sort[title]]">
+<$link to=<<currentTiddler>>><$text text=<<currentTiddler>>/></$link>
+</$list>
 </div>
 </$list>
 </div>