Passing the map to Map.get_lazy's function

[David Long]

I was working on some code that would simply test if one key was in a map and return it's value, and otherwise return a different key's value.

The map had a form like the following:

%{

  oncall: "dlong",

  overrideoncall: "jsmith",

  ...

}

If there was someone overriding on call then their name would be in the `overrideoncall` key, otherwise the key would not be in the map.

I think this could be a nice use for `Map.get_lazy`, if the function had the original map passed in, allowing me to write the code as follows:

Map.get_lazy(on_call_group, :overrideoncall, &(&1[:oncall]))

Before I wrote a pull request, I thought I'd see if this is a feature that makes sense to others?

[José Valim]

The reason why get_lazy does not pass the map is because you already have the map, since you pass it as first argument.

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[David Long]

That's not entirely accurate. In my case I was using a series of pipes so I did not have access to the map. My case might be very niche, though.

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[Ben Wilson]

Can you elaborate on the code you have in mind? This sounds like a general characteristic of pipes and not something specific to Map.get_lazy.

[David Long]

Hi Ben,
My issue is specific to pipes. What I'm ultimately doing is taking a JSON object, parsing it with Poison.decode!, And then attempting to pull a single key out, either overrideoncall or oncall.

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[Michał Muskała]

You could define a helper function, for example:

defp map_get_any(map, keys), do: Enum.find_value(keys, &Map.get(map, &1))

That could be used like this:

data

|> Poison.decode!

|> map_get_any(["foo", "bar"])

Michał.

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[José Valim]

That's not entirely accurate. In my case I was using a series of pipes so I did not have access to the map. My case might be very niche, though.

All the capabilities all there. Not all functions in the standard library can be pipable on all cases exactly as you want.

Define a private functions and you should be golden.

[David Long]

Than you all. I did implement a private method. I just thought I'd put out there, the suggestion of making the `Map.get_lazy` method a little more pipe friendly.