> 1. Do you think anyone would purposefully name a variable a type? (false
positives.)
Yes, we do it in Elixir all the time. Because if I am implementing
String.downcase/1, the name `string` is a very good name for the argument:
def downcase(string)
And since we use names in the docs, calling it `my_string` may even be
confusing.
Furthermore, variables and types live in distinct namespaces. There is no
way one can clobber or shadow the other, so overall this is not a concern.
There is a concern of a developer choosing a poor variable name, but that's
not related to types at all. You can give bad names to your variables, even
if they don't match a type at all. :)
On Fri, Jan 12, 2024 at 7:05 PM Robert Viragh <rvir...@gmail.com> wrote:
> This proposes you should add a warning if a programmer names the variable
> with the name of a type - what do you think?
>
> Motivation
> Ahead of the recent gradual typing introduction, I was having fun
> exploring types and was trying to come up with cases that are definitely a
> type mistake but that the current version of Elixir wouldn't catch as a
> warning or error.
>
> One case I found is something a programmer probably wouldn't do
> intentionally, and could be worth warning about.
>
> Currently, you can name a varaible as a built-in type, for example this is
> correct code:
>
> # Set the variable named "integer" to the string "42". Despite its name it
> is a string.
> integer = "42"
>
> # This is now valid:
> # Define a map with string keys
> profile = %{
> "age" => integer,
> }
>
> # Access data from the map
> age = profile["age"]
> IO.puts("Age: #{age}")
>
> Try it. It will print:
> iex(9)> IO.puts("Age: #{age}")
> Age: 42
> :ok
>
> It's a string all along and someone might wonder why they're seeing
> bizarre code like that, but as more types got introduced it would be more
> likely that programmers learning the syntax would *accidentally* name a
> variable by the name of a type. Polymorphic code could eventually lead to
> tricky issues.
>
> What I think should happen is that the line:
>
> integer = "42"
>
> should warn:
>
> Warning: variable named with the name a type. This is probably not what
> you want. Consider changing the name of a variable so that it is not also
> the name of a type, for example rather than
> integer = "42"
> you could name it:
> my_string = "42"
> In this case "my_string" is no longer the name of a type.
> "
>
> What do you think about this proposed warning?
>
> 1. Do you think anyone would purposefully name a variable a type? (false
> positives.)
> 2. Do you think it could be useful for catching future syntax errors,
> especially as the type system becomes more fleshed-out and there is more
> polymorphic code? (true positives)
>
> The warning could also be useful once more types are used in the future.
> A local variable should not accidentally shadow the name of a type without
> warning.
>
> This warning can be added to the current version of Elixir and does not
> depend on gradual typing.
>
> Best regards,
> Rob
>
> --
> You received this message because you are subscribed to the Google Groups
> "elixir-lang-core" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to elixir-lang-core+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/elixir-lang-core/5f713616-b9e8-4ad5-b2eb-6a51327c8bf4n%40googlegroups.com
> <https://groups.google.com/d/msgid/elixir-lang-core/5f713616-b9e8-4ad5-b2eb-6a51327c8bf4n%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
You received this message because you are subscribed to the Google Groups
"elixir-lang-core" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to elixir-lang-core+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4%2BLp0Pn6atjB1RRxap4Ww%2BdookYqJPyM%2BZvy_ng2Dve6Q%40mail.gmail.com.
