38 lines
2.2 KiB
Markdown
38 lines
2.2 KiB
Markdown
[[!template id=gitbranch branch=GiuseppeBilotta/scanif author="Giuseppe Bilotta"]]
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When a directive that should be run during scan preprocessing is inside
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an if directive, it doesn't get called because the if preprocessing does
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not run during scan.
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I've written a simple [[patch]] to fix the issue, currently hosted on the
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scanif branch of my repository. The patch also passes the preview option
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back to the Ikiwiki::preprocess call, making sure that whatever is being
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reprocessed is done so in the same conditions as the original call.
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> One problem with this is that it has the same dependency-ordering problems
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> as inline-based or pagespec-based trails with my [[plugins/contrib/trail]]
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> plugin: `if` takes a pagespec, but pagespecs aren't guaranteed to match
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> correctly until everything has been scanned (for instance, `link()` might
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> give the wrong results because a page that added or deleted a link hasn't
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> been scanned yet). If you have a clever idea for how to fix this, I'd love
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> to hear it - being able to specify a [[plugins/contrib/trail]] in terms
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> of a sorted pagespec would be useful. --[[smcv]]
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>> I have a solution to the dependency-ordering problem in a different
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>> branch of my repository, with a post_scan hook mechanism which I use to
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>> be able to sort outer inline pages according to the last modification
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>> date of their nested inline pages. The way I implemented it currently,
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>> though, doesn't use the existing hooks mechanism of ikiwiki (because
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>> it's something which I believe to be more efficiently done the way I
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>> implemented it) so I don't know how likely it is to be included
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>> upstream.
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>> For what it's worth, I think that my post_scan hook mechanism would work
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>> rather fine with your trail plugin. However, the case of the if
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>> directive is considerably more complicated, because the conditional
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>> can introduce a much stronger feedback effect in the pre/post scanning
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>> dependency. In fact, it's probably possible to build a couple of pages
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>> with vicious conditional dependency circles that would break/unbreak
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>> depending on which pass we are in. And I believe this is an intrinsic
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>> limitation of the system, which cannot be solved at all.
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