CODEWITHSUNDEEP
scala
alex
alex

Reputation: 1917

Create class attributes dynamically in Scala

Is it possible to create a class (or add attributes to a class) dynamically, e.g. load field names and types from external file in Scala?

this is follow-up on Representing nested structures in scala

Upvotes: 1

Views: 1002

Answers (2)

Eugene Burmako
Eugene Burmako

Reputation: 13048

It is possible to achieve this with macros, and there are two techniques for that with a different set of trade-offs. Refer to our joint talk with Travis Brown for more information and a link to an example implementation: https://github.com/travisbrown/type-provider-examples/blob/master/docs/scalar-2014-slides.pdf?raw=true.

Upvotes: 2

Bob Dalgleish
Bob Dalgleish

Reputation: 8227

You can declare and compile a Scala class from a data structure description. It requires that you a) construct a syntactically correct class description and save it to a file (or equivalent) and then b) compile that class description to object code (i.e., a .class file). You can then load the class and use it.

This is not for the faint of heart. You need to understand the process of translation, compilation, class-loading and dynamic class binding. Even more important, you have to answer how you would actually use this in a program.

An example of dynamic class creation occurs in the Scala Play framework, where a presentation template files are translated into Scala and compiled into class files that can then be referenced from other Scala source code.

Upvotes: 2

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