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Hello, |
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There has been some debate whether we should be using plain '?' |
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USE-dependencies or the USE-default form '(-)?'. I have reviewed |
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the practical differences between them (using portage), and I'd like |
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to shortly summarize them. |
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Just for clarity, the general problem: dev-python/foo depends |
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on dev-python/setuptools. Therefore, the Python implementations enabled |
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in dev-python/foo, need to be enabled (and supported) in setuptools |
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as well. |
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The 'flag?' syntax requires the dependency to have flag in IUSE |
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(the implementation in PYTHON_COMPAT). If it's not there, the package |
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does not satisfy the dependency *even if* the flag is disabled. |
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IOW, dev-python/foo deps on dev-python/bar. foo has python3_3 |
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in PYTHON_COMPAT, bar-2 does not. Even people with python3_3 disabled |
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won't be able to emerge bar-2 as a dependency of foo. |
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The 'flag(-)?' syntax assumes that a missing flag in the dependency |
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is equivalent to the flag being disabled. In this particular case, it |
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means that the dependency won't be satisfied if py3.3 is enabled. |
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That was for the formal part. Now the practical implications. |
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1. No version of the dependency supports the requested implementation: |
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portage: with both variants, refuses to merge the package, shows a bit |
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about missing USE flags |
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repoman: with 'flag?' variant, complains about it for most profiles with |
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an error of missing dep. with 'flag(-)?' variant, no errors nor |
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warnings. |
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+1 for 'flag?' |
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2. The newest version of the dependency doesn't support the requested |
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implementation: |
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portage: |
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- with 'flag?', always uses the older version, |
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- with 'flag(-)?', uses the older version only if the unsupported |
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implementation is enabled. |
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repoman: no errors nor warnings. |
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+1 for 'flag(-)?' |
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I'd say that the both cases are not 'good enough'. 'flag?' is a bit |
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saner for QA, 'flag(-)?' for when QA fails (and people use repoman |
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--force because they NEED that python3.3 so much)... |
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Maybe we should make repoman more paranoid about missing flags |
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in the first place? |
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-- |
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Best regards, |
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Michał Górny |
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