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    <p>Are your examples real code, or just examples?</p> <p>If they're real code, I think you overuse decorators, probably because of your background (i.e. you are used to other programming languages)</p> <h3>Stage 1: avoiding decorators</h3> <pre><code>def run(rootnode, func): def _run(node): # recursive internal function func(node) for x in node.children: _run(x) # recurse _run(rootnode) # initial run </code></pre> <p>This run method obsoletes makeRunner. Your example turns to:</p> <pre><code>def pp(n): print "%s," % n.val run(tree, pp) </code></pre> <p>However, this ignores completely generators, so…</p> <h3>Stage 2: using generators</h3> <pre><code>class Node : def __init__(self,val,children) : self.val = val self.children = children def __iter__(self): # recursive yield self for child in self.children: for item in child: # recurse yield item def run(rootnode, func): for node in rootnode: func(node) </code></pre> <p>Your example remains</p> <pre><code>def pp(n): print "%s," % n.val run(tree, pp) </code></pre> <p>Note that the special method <code>__iter__</code> allows us to use the <code>for node in rootnode:</code> construct. If you don't like it, just rename the <code>__iter__</code> method to e.g. <code>walker</code>, and change the <code>run</code> loop into: <code>for node in rootnode.walker():</code><br> Obviously, the <code>run</code> function could be a method of <code>class Node</code> instead.</p> <p>As you see, I suggest you use directly <code>run(tree, func)</code> instead of binding them to the name <code>printTree</code>, but you can use them in a decorator, or you can make use of the <code>functools.partial</code> function:</p> <pre><code>printTree= functools.partial(run, func=pp) </code></pre> <p>and from then on, you would just</p> <pre><code>printTree(tree) </code></pre>
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    1. POWhy Python decorators rather than closures?
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    1. COWhile using iterators is often nice, I find your rewrite much worse. It's _very non-obvious_ what "for item in child: # recurse" is doing, even with the comment. The original code using just functions is more obvious, and smaller.
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      1. USJames Antill
    2. COΤΖΩΤΖΙΟΥ, it was a contrived example to illustrate my question; although based on similar things I've done in the past. Thanks for your alternatives. Interesting. I've certainly used the stage 1 form before, but don't think I've ever done tree-running with iter.
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    3. COACtually, looking at your last point, why would you prefer functools.partial to the decorator version? (ie. what are the pros and cons of each?)
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