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59 lines
2.2 KiB
59 lines
2.2 KiB
5 years ago
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title = "Things I Learnt The Hard Way - If Your Data Has a Schema, Use a Structure"
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date = 2019-06-25
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[taxonomies]
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tags = ["en-au", "books", "things i learnt", "data classes", "structs"]
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You may be tempted to use a list (or tuple, if your language allows) to keep
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your data if it's simple -- like, say, only 2 fields. Don't.
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<!-- more -->
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Some languages allow unstructured data to be kept in the format of tuples:
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They act like lists, but you can use to store heterogeneous data (which is a
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cute way of "it stores fields of different types").
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This languages also allow you to "destructurize" them, so you can extract
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elements from them without directly accessing them by index.
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For example, in Python, you can have a tuple with:
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```python
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a_tuple = ('A String', 1, 7.5)
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```
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And you can destructure it with
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```python
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some_string, an_integer, a_float = a_tuple
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```
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See? It's simple! You don't need to create a whole structure if you're just
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passing a string, an integer and a float around.
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Except, you do.
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Tuples and destructuring should be used only when you need to pass data from
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one function to another -- and barely that. When you have this tuple being
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passed around, being destructured and created again -- say, you are adding one
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value of the tuple to another value and producing a new tuple in the same
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format -- then you have a structured data.
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And when you have a structured data, you must use a data class or a struct (or
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even
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[NamedTuples](https://docs.python.org/3/library/collections.html?highlight=namedtuple#collections.namedtuple),
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if you're using Python).
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Although it may look way more simpler to keep destructuring and building the
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tuple over and over, in the long run you'll end up with a mess 'cause a simple
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change -- like adding a new field -- will require checking every destructuring
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and every creation of the tuple to make sure if will stay in the same shape
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every time.
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So: You data has a schema? Use a Data Class or Class or Struct. Only if it is
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schemaless, then you can use a tuple.
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{{ chapters(prev_chapter_link="/books/things-i-learnt/data-types", prev_chapter_title="Types Say What Your Data Is", next_chapter_link="/books/things-i-learnt/languages-are-more", next_chapter_title="A Language Is Much More Than A Language") }}
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