Default values and required values #864
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There was no mention of not passing default values or requiring some fields to be passed a value.
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| ## Default values and required values | ||
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| If you don't specify default field values when defining a struct, **nil** will be assumed: |
| iex> defmodule Product do | ||
| ...> defstruct [:name] | ||
| ...> end | ||
| iex> prod = %Product{} |
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No need to bind the newly created struct to prod here :) We can just show %Product{}.
| @@ -113,3 +113,27 @@ iex> Map.keys(john) | |||
| ``` | |||
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| Structs alongside protocols provide one of the most important features for Elixir developers: data polymorphism. That's what we will explore in the next chapter. | |||
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| ## Default values and required values | |||
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Maybe "and required fields"? Wdyt? Not sure about this one.
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shouldn't they be keys ?
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@eksperimental I think we use key and field interchangeably in structs, personally I prefer fields but any one of them is ok.
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the thing is error messages in the example use "key", and we are using an attribute called "@enforce_keys"
| ...> @enforce_keys [:make] | ||
| ...> defstruct [:model, :make] | ||
| ...> end | ||
| iex> car = %Car{} |
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Same as above, we don't need the car variable.
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| ## Default values and required values | ||
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| If you don't specify default field values when defining a struct, `nil` will be assumed: |
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I think it should read "If you don't specify a default field value", since only one value can be assigned.
| %Product{name: nil} | ||
| ``` | ||
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| You can also enforce that certain fields have to be specified when creating the struct: |
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keys is what docs uses to refer to fields: "You can also enforce that certain keys have to be specified"
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Looks good to me, thank you @edevil. ❤️ @whatyouhide, please merge when you are ready. |
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| ## Default values and required keys | ||
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| If you don't specify a default field value when defining a struct, `nil` will be assumed: |
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Since we're calling the structs fields "keys" everywhere apparently, let's fix this to be "[...] a default key value [...]" and then we're good to go!
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Thanks a lot @edevil! 💟 |
There was no mention of not passing default values or requiring some fields to be passed a value.