[SystemSafety] Modelling and coding guidelines: software components

[GRAZEBROOK, Alvery N]

On the principle of nudging folk in the right direction, it seems to me that the use of non-executable annotations (e.g. SPARK) is a valuable contribution for defining a library interface contract that would make software component re-use more checkable. 

Does anyone know of similar annotation schemes on language subsets of C, C++ or other more widely used languages? If this concept were to become more widely available, it could have a big impact on the expectations for "good quality" software components and be used in areas where regulations don't reach. 

Cheers,
	Alvery

[snip]
> Whether we like it or not we are all
>involved in component based design. My experience with software 
>libraries is that there are some good ones out there that are quite 
>stable. On the negative side I have two problems with them:
>1. They are almost universally very poorly documented so you can waste 
>a day trying to achieve a trivial outcome.

I agree that many examples of software components I have seen have lacked sufficient documentation to be able to make sensible decisions about suitability. I find that if you can chuck it back via the author to get that improved, the documentation improvement is sometimes worthwhile. Otherwise you end up writing it yourself.

>2. The authors seem to have no concept of backward compatibility. 
>If you make the mistake of upgrading to the latest version you can 
>trash your complete application: data structure changes, even method 
>name changes. Amazing!#

Regression testing is part of the regimen and any new version has to pass all the old tests as well as any new ones. There is a strict notion of how much impact changes at lower levels will have on the upper layers of the application. I'll happily explain about surfaces to you at some stage.
[snip] 

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