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.

In reply to Re^7: "When code reuse turns ugly" by hippo
in thread "When code reuse turns ugly" by BrowserUk

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