When are libraries inserted into a Simulink model?

Custom library blocks are stored in their own library files, and the model that uses them contains library links to these blocks. As these library blocks are not stored in the actual model, how and when are the inserted into the model? Pre-compile time? During model compilation? I can't find any sources that explicitly say.

I am trying to understand how library blocks work. Are they basically like C macros?

Answer 1

[Hadi Zyien]

You are correct: Library linked blocks do not actually store the library block in the model in which they are used. Rather, the blocks store a link to the source library block. You can see this by looking at a block's 'ReferenceBlock' parameter. Whenever a model is loaded or updated, the links will update.

So yes, you can make the analogy that a library block acts like a C macro (both function-like or object-like, depending on if there are block inputs). A C macro is pre-processed prior to compilation, where all occurances are replaced. Likewise, pre-model-compilcation all library links will be updated.

More information on Libraries can be found here: https://www.mathworks.com/help/releases/R2018b/simulink/ug/creating-and-working-with-linked-blocks.html