[Template] Multi-File, Multi-Class with SharedConstants Mixin

Developers Ruby API
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SketchUp Extension Template

Multi-File, Multi-Class with SharedConstants Mixin Module

Warning! This coding pattern is not allowed in Ruby 3 (SketchUp 24+)

Class and Module @@ variables can no longer be shared across class or module scopes.
Myself, I do not like this change as it removes the power of @@ variables. But apparently too many coders did not understand how to use them, so the Ruby Core project basically “dumbed them down”.
In Ruby versions previous to 3, we could have multiple classes and modules sharing @@ variables by inclusion from a mixin module. Any of the sharing classes or modules could make changes to the shared variables. In Ruby 3, instead a warning is generated and a unique @@ variable will be created in the mixee class or module, thereby defeating the shareability.

Going forward, we will need to define an object (a module or a class instance) that holds the variables and data to be shared, and the various other modules and classes would access the variables and data via singleton or instance methods calls upon the shared object.

MultiClass_MultiFile.zip (3.9 KB) - UPDATED 2024-05-10

Change module name “Author” in the template files to your own unique top-level company name, brand name, initials, or online nickname. (Do not use some other entity’s trademarks, salesmarks, brandnames, patented names, etc. Ie, do not use “Sketchup” or “Layout” in any form, in any case combination, with or without appended or prepended words.)

Change the “MultiClassPlugin” sub-module name (in all files,) to the name of your particular plugin.

Save your template as encoding UTF-8 without BOM (Bit Order Mark.)
It is also recommend that Unix type end of lines be used. (Although some prefer Windows EOLs on PC because snippets can be pasted into the Ruby Console and line breaks work. Snippets with Unix EOLs will not line break in the PC console. I personally have only the little snippet files in my “Snippets” folder set to Windows EOLs.)

:bulb:

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Updated : 2017-12-29

Added an actual "SharedConstants.rb" file showing the
definition of the Author::MultiClassPlugin::SharedConstants module.

Although from the code examples, it was implied that this file must exist, many new coders did not understand this, so I was asked to actually provide this file.

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Hi Dan,

Thanks for putting this template together, I’m finding it very helpful as I dive into learning Ruby and the SketchUp API. I just wanted to let you know of a typo in Author_MultiClassPlugin.rb. On line 28, the method name should refer to SketchupExtension.creator instead of SketchupExtension.creater. I tried to create an extension with your template and SketchUp threw an error on load. undefined method 'creater='

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Hi Matt

Alternatively you can use this as template: open-newer-version/ene_open_newer_version.rb at master · Eneroth3/open-newer-version · GitHub.

This example gets the extension dir name from the loader file name, so you don’t need to manually edit it for new extensions. By the RBZ specification these names must be the same anyway. It also keeps a constant as reference to the extension object, allowing you to easily reference it in any nested classes or modules, e.g. to use its name for menu entries, or if you need to get its version string.

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Very cool Christina, thank you! I was actually just playing around with the UI::Notification class, scratching my head on how to retrieve the extension object. Having that constant defined makes it easy.

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UPDATED 2024-05-10

Changed the registrar file:

  • Use Julia’s idea where it gets the extension subfolder name from the registrar’s filename.
  • Fixed the typo reported by @Matt
  • Changed the reference @@extension to a local module constant EXTENSION
  • Use an instance_eval block to set the attributes

Added a dedicated loader.rb file that uses Sketchup.require so that the extension files can be RBE encrypted. The files are loaded in the order that they need to be evaluated from an array of literal filenames.

Shortened the filenames inside the extension subfolder.

Added a "Main.rb" and a "GUI.rb".

Changed the "ClassThree.rb" file to a "SupportSubModule.rb" just to show that another submodule inside the extension is possible.

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See the comments in the original post.