Idea Delivered

This is being delivered in XPP 9.4

xyPerl: need a better way to check the current context

In xyPerl you can easily check for the presence or get the value of an attribute from a specific ancestor using the rather elegant syntax provided (@name, ../@name, ../../@name, ancestor::element/@name, etc...)

But checking if you are in a certain context is quite cumbersome. You need to do a get_mlh or get_path and then write your own function to detect if you are currently in a certain context.
This could be done a lot easier if we could use similar syntax like for the attributes inside a new xyPerl function (get_context?)

Things could look like this:
if ($X->get_context('ancestor::chapter') ) {
   doSomething();
} else {
   doSomethingElse();
}

Remark: one might argue that the context checking might be done inside the CSS, but sometimes you just want to avoid writing 2 similar xyPerl functions and just to the context checking inside your xyPerl function.

Bart Terryn
Parents

  • This seems like a good idea to me. Granted, in a "pure" world, everything is CSS, but as we know sometimes you just need to do a little perl. Having the ability to test the current document hierarchy can simplify some of the perl and allow for sharing.

    So, I'm thinking, we can support some of the Xpath axis statements; as  $X->check_context('Xpath axis") where 'axis' is the keyword and tag name to test as:

       ancestor::foo - any ancestor node named 'foo'
       ancestor-or-self::foo - any ancestor or current node named 'foo'
       parent::foo - Current node's parent name is 'foo'
       self::foo - Current node's name is 'tag'

    A non-empty string return is TRUE, "" is FALSE

    What do you think?


  • in reply to Steve Piercey

    $X->check_context() is indeed better than $X->get_context.
    And the the proposed Xpath axis statements are fine. 
    But I would like to see the '.' possibilities as with the $X->get_attr() function:
    ./foo
    ../foo
    ../../foo 

  • in reply to Bart Terryn

    (ai hit the return key too quickly)

    ../../ ... ../foo
    (especially the grandparent test might be useful)

Comment Children