several question about book migration

[Superjomn]

• should the python syntax be exactly the same with V2 API?

  • currently, we have some new concept such as executor, default_program, fetch_list
  • some new concepts bring flexibility(such as while op) and are hard to hide as the underlying of V2 API.

• when the book based on Fluid is completed, should we discard the old V2 content?

  • during migration, new content will be placed to a chapter_xxx_fluid directory
  • the new Fluid content can co-exist with the V2 content.
  • if we want to drop V2 content, just replace them with chapter_xxx_fluid.

[kavyasrinet]

In addition to the list above, we should also discuss the following/ add them to our TODO list:

1. Have documentation for the new concepts we have introduced in fluid as mentioned above.
2. The python files as of now do not have a 1:1 mapping from the fluid/test/book to the chapters of the book. We should re-write that part and combine different implementations if required (for example : recognize_digits and understand_sentiment).
3. Plot the training curves again using the fluid code.
4. Rewrite code snippets back to the book's markdowns.

[wanghaoshuang]

when the book based on Fluid is completed, should we discard the old V2 content?

We had better keep the V2 content accessible. By default, we can show chapter_xxx_fluid in this page. And attach the hyperlink of relevant V2 content in each chapter.

[dzhwinter]

Considering V2 API released no longer than one year, it's better to keep compatible with V2 API. We aim to deliver an industrial-grade framework, frequently changing the API will lose users confidence.
So the question converts to how to keep compatible with V2 API. In Fluid, our design philosophy is totally different from previous ones, there is some fundamental concept need to expose, such as Program, LoDTensor.

1. Create A Fluid directory, put the new implementation into it.
   Because book with V2 API is a stable version, but the Fluid books are not. We still keep polishing the Fluid books, will swap the for loop with while op in next stage.

2. Add deprecated warning message to old API, and give a good suggestion in our document, then people will accept the Fluid more smoothly.

[shanyi15]

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