Installable Transforms

[svandragt]

A model currently declares a structure, which describes the sections within a record. The structure is an array of field / transform pairs. Cuttlefish comes with markdown and metadatareader transforms, but we want the user to install and use their own. There is currently no registration method and extensibility to allow this, so this is not currently possible.

see https://github.com/svandragt/cuttlefish/blob/c432589449b8ee743862c11b051faadfd90c38d3/src/system/Model.php#L87

In the code above the transforms are hardcoded. Therefore there needs to be a registration system where a transform registers and then the register can be searched to match the model structure.

Previously: Model section explicitly has loading mechanisms for metadata and markdown. This should be part of the metadata and derived markdown class implementation respectively. This can be achieved using a trait, I think. Then content includes svandragt/cuttlefish-blog#2 can use this mechanism to register themselves and provide a loader for a content section.

• [ ] The application can register user transforms
• [ ] The application can use user transforms in content
• [ ] End user documentation

[svandragt]

this is duped by svandragt/cuttlefish#67

[svandragt]

Maybe I shouldn't have removed the loaded_classes passing as I have in svandragt/cuttlefish#88. Would prefer to use some kind of hooking system ala wordpress.