Plugins

Plugin system based on libpeas. Plugins may implement multiple extension points, each providing specific functionality.

General design principals and rationale:

• Each extension is defined by an interface, so multiple may be implemented by one plugin
• Extensions provide access to context objects that plugins use to do real work, so that additional features can be added (to the context) without breaking existing implementations of an extension
• A context instance is created per plugin, so they can be disposed of when a plugin is deactivated
• Resources obtained from contexts are proxies for the underlying engine objects, so the API surface can be controlled and access restrictions enforced
• Resources are obtained from contexts via async methods, so that permission can be requested from people via a UI prompt before returning the resource

Notification Plugins

Requires access to inbound/outbound email, folders identities & metadata (but not email content), contacts, avatars.

Permissions:

• Email
• Folders
• Contacts

Email/Conversation Plugins

Requires access to individual email messages, their parts and contents.

Use cases

Drafts/Templates

• Display info bar when loaded (depending on folder?)
• Add action specific to the email to the info bar
• Execute command to edit message in composer when activated

Diffs

• Access email parts when loaded
• Add diff widget to email view

Calendar

• Access email parts when loaded
• Add calendar widget to email view
• Add action specific to the email to the info bar
• Execute DBus/external command to create calendar part

Prefer plain

• Access email parts when loaded
• Override default email body view

Permissions:

• Email
• Folders?

Folder Plugins

Use cases

Trash/Spam

• Display inforbar when selected
• Add action specific to a folder to the info bar
• Execute command to empty trash when action triggered

Templates

• Display inforbar when selected
• Add action (specific to a folder?) to the info bar
• Open augmented composer

ACL

• Register per-folder action
• Send commands to the server?
• Store/cache data?

Quota

Probably account-based, but may want to show per-folder storage use?

• Register per-folder action
• Send commands to the server?
• Store/cache data?

Permissions

• Folders (metadata, not email content)
• Server

UI hooks

Display infobar when a specific folder is selected. Should use a signal with a specific context argument so that they can be added without requiring state to be maintained.

Per folder actions can be added when folders added/removed/changed type - which is notified per by signals.

Folder action interface receives signal when action activated.