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PO"Flat is better than nested" - for data as well as code?
 

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  1. PO"Flat is better than nested" - for data as well as code?
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    <p><a href="https://stackoverflow.com/questions/4372073/traversing-and-modifying-a-tree-like-list-of-dict-structure/4372174#4372174">This</a> question got me thinking: should we apply the principle that "flat is better than nested" to data as well as to code? Even when there is a "logical tree structure" to the data?</p> <p>In this case, I suppose it would mean representing children as a list of IDs, rather than an actual list of children, with all the nodes in a single list:</p> <pre><code>[ {'id': 4, 'children': ()}, {'id': 2, 'children': (1, 7)}, {'id': 1, 'children': (6, 5)}, {'id': 6, 'children': ()}, {'id': 5, 'children': ()}, {'id': 7, 'children': (3,)}, {'id': 3, 'children': ()} ] </code></pre> <p>(I used tuples because I prefer not to give myself the flexibility to mutate an object until that flexibility proves itself to be useful and usable in a clear manner. In any case I would never use <code>None</code> here instead of an empty sequence, because it complicates the logic, and "special cases aren't special enough" - here, it isn't special at all.)</p> <p>Certainly this is shorter, but the tree structure is obscured. Does that contradict "explicit is better than implicit"?</p> <p>Personally I find that "flat is better than nested" is of limited applicability, and nowhere near the most important aspect of the Zen. (Certainly I could not do a lot of the nice functional-programming things that I do if I didn't allow myself significant nesting.) I suspect that the problem with "nested" is that it requires context switching when you comprehend the information. I really think this is more of a problem when following imperative logic than for parsing data or functional-style code - where it's easier to just mentally name the nested block, and consider its workings separately from the outer context.</p> <p>What say you?</p>
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    1. USKarl Knechtel
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    1. COGood question, as the asker of the question you linked I am curious as well. I would prefer not to obscure the tree structure but what you have in your post would certainly simplify the approach for performing an operation on each node in the tree. Looking forward to seeing what others think.
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      1. USAndrew Clark
    2. COI think you have to bear in mind the context that aphorism was made in. Python allows a certain degree of functional programming, but ambivalently (for instance destructive operations don't return values, closures are subtly broken, etc.) I don't think it would even occur to most people who mainly do pure functional programming to prescriptively say that flat is better than nested. If what I am operating on is a tree, I would rather see it represented as a tree.
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      1. UST Duncan Smith
    3. COTerrible question. Conflating data with source code is like comparing an island and the Empire State Building. Yes, the building is located on an island, but that's the only relationship they have.
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