in reply to Re^6: "When code reuse turns ugly"
in thread "When code reuse turns ugly"

Someone way down stream publishes a change that breaks something (or several somethings) higher up in a subtle way; the upstreamers go into frantic overload to write workarounds and publish; their upstreamers do the same; and your project falls in a heap because of it.

I think you have your ups and downs reversed - easy to do if not used to the metaphor. NEILB has written quite a bit on this, see The River of CPAN for an introduction. There's been some work to mitigate the problem which you've highlighted but so long as there are dependencies it will never entirely vanish.

The point about Continuous Integration is that it requires 100% adherence to strict testing. This means that you have a build process which includes a full test cycle before the newest deps get anywhere near production. CI sounds good but it's a lot of work to get any robustness into it as hopefully should be obvious to most.

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Re^8: "When code reuse turns ugly"
by BrowserUk (Patriarch) on Mar 31, 2016 at 13:34 UTC
    The point about Continuous Integration is that it requires 100% adherence to strict testing.

    Which is fine and dandy if your dependency supplier's are as rigorous as you are. You have that confidence?

    The point is that dependency changes don't have to make it through your testing to affect your development.

    And, with programmers writing the tests that verify their own code, if a dependency programmer gets the wrong end of the stick; or has a bad day, his code probably will satisfy his tests and make it through to his production branch without error. And it may not break the intermediaries test -- they haven't written any tests for the specific change and nothing breaks in their code, so it gets waved through by the automated processes.

    Its only when it hits you that things break. What do you do? Back out the automated change and hope it'll go away? Or try to write a fix?

    If you back out the change; what happened to Continuous X? And how long do you wait before trying again?

    And if you look for a workaround; how much effort should you expend given the possibility that you'll have to revert it all next Wednesday?

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