What do people think about this suggestion:
```elixir
defmodule Thing do
def put_if(map, value_to_check, new_values) do
Enum.reduce(map, %{}, fn
{key, ^value_to_check}, acc -> Map.put(acc, key, Map.get(new_values,
key))
{key, value}, acc -> Map.put(acc, key, value)
end)
end
end
new_values = %{
foo: 10,
bar: 20
}
Thing.put_if(%{foo: nil, bar: 10}, nil, new_values)
# => %{bar: 10, foo: 10}
Thing.put_if(%{foo: false, bar: 10}, false, new_values)
# => %{bar: 10, foo: 10}
Thing.put_if(%{foo: nil, bar: 10}, false, new_values)
#=> %{bar: 10, foo: nil}
```
That would give you the ability to replace something if it was nil or false, or
whatever you wanted?
Best
Adam
> On 23 Jul 2020, at 14:26, Zachary Daniel <[email protected]> wrote:
>
> I would use this function pretty often if it existed :)
>
> I'm not really a fan the `update_if` that Jose proposed because my biggest
> use case has been "update a key, but I don't want to put a default in if it
> doesn't exist". I think something like
>
> `Map.update_existing(map, :key, fn value -> value * 2 end)`
>
> You can also simulate the "update if" by putting a conditional in the
> function like `if value != nil, ...`
> On Thursday, July 23, 2020 at 9:20:35 AM UTC-4 Riccardo Binetti wrote:
> Hi everybody,
> I would like to bring this proposal back since I just typed `def put_if`
> again in another module :)
>
> Being my first proposal I don't know what is the usual process, but I think
> the discussion showed that there is some interest in this functionality.
>
> I personally like the `update_if` proposal made by José because it's a more
> general construct that can be useful in various situation. I wouldn't mind
> also having a `Map.put_if` function in the Map module but I'm fine using
> `update_if` in case.
> --
> Riccardo
>
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