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POImplement Apect-oriented-like nested around filters with Ruby?
 

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    <p>I'm trying to write a class that supports nested around filters without introducing an Aspect-oriented library.</p> <pre><code>class Foo attr_accessor :around_filter def initialize #filters which wrap the following one are the ones with interesting logic #vanilla do-nothing filter @around_filter = lambda { yield } # or lambda {|&amp;blk| blk.call} end def bar #would execute the around filters however deeply nested, then "meaty code" @around_filter.call do #meaty code here puts 'done' end end #I expected to point only to the topmost filter, hoping to recurse def add_around_filter(&amp;blk) prior_around_filter = @around_filter @around_filter = #??mystery code here?? refers to prior_around_filter end end </code></pre> <p>The goal is to be able to add any number of around filters:</p> <pre><code>foo = Foo.new foo.add_around_filter do puts 'strawberry' yield puts 'blueberry' end foo.add_around_filter do puts 'orange' yield puts 'grape' end foo.bar #=&gt; orange, strawberry, done, blueberry, grape </code></pre> <p>I know there are a bunch of holes in the example. I wrote only enough to covey the general direction, distilling from a much larger actual class.</p> <p>Although I prefer <code>yield</code> syntax, I'm not opposed to block references:</p> <pre><code>foo.add_around_filter do |&amp;blk| puts 'orange' blk.call puts 'grape' end </code></pre> <p>I got this working only with a single around filter. I tried lots of things with nesting, but never cracked the puzzle. If you have a solution, I'd appreciate it a bunch! </p>
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