Re: [Qemu-devel] new to qemu with a simple question

[Eric Blake <eblake@redhat.com>]

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On 05/23/2017 09:56 PM, Wang Dong wrote:
> 
> Hi guys,
> 
> I am new to qemu. But I need do some job in it right now.
> 
> When I try read qmp code. I found a interesting part against it.
> 
> Some C source code is generate from json file.
> 
> I wonder why this? What is the benefits of this?

Boring and repetitive code that is easy to typo is best written by a
computer, which excels at boring and repetitive tasks.  Writing our
description in a more concise higher language and generating C code from
that lets us focus on the actual design, rather than the mundane
correctness of the code implementing the design.

It's the same reason that people use bison/yacc rather than hand-written
parsers for complex grammars - you isolate the correctness of the code
to the correctness of the generator, and free yourself to now only have
to worry about the bigger picture of the input you feed to the
generator.  And on another level, it's why we write programs in C
instead of assembly.  Abstraction is good.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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