Validate the default value for prop and data against to the given type

[Malian]

The current implementation allows the following code:

prop title, :string, default: 0

We could check that the default value respects the type string at compile time and raise a CompilationError if the default value does not match the given type.

We should be able to perform this validation for the following types:

• :list
• :boolean
• :string
• :time
• :date
• :datetime
• :naive_datetime
• :number
• :integer
• :decimal
• :map
• :fun
• :atom
• :module
• :keyword
• :struct
• :tuple
• :pid
• :port
• :reference
• :bitstring
• :range
• :mapset
• :regex
• :uri
• :path

[yusufyildirim]

It would be great if we could check if the given default value exist in the values list also.

For example:
prop weight, :string, values: ["light", "normal", "medium", "semibold", "bold"], default: "something_else"

This complies and does not throw any error even though the given default value does not exist in the values list.

[Malian]

@yusufyildirim good catch!

I believe we could add this to the maybe_warn_mutually_exclusive_opts and rename the method to maybe_warn as suggested by @msaraiva in #283 (comment)

A simple check like this should do the trick.

values = Keyword.get(opts, :values, nil)
default = Keyword.get(opts, :default, nil)

if default && values && default not in values do
  IOHelper.warn("A proper message", caller, fn _ -> caller.line end)
end

Maybe we should handle the case of an accumulate prop where the following code is valid and where my quick solution will not work:

data count, :integer, default: [], values: [0, 1, 2]

Would you like to open a PR?

[yusufyildirim]

Hi, @Malian. First of all, thank you to all the maintainers for this project.

I'm pretty new to the language and the ecosystem in general but It looks easy enough to fix and I think I can do that 😄 I'll look into it on the weekend.

Thank you for the tip!

[msaraiva]

This will be addressed by LV itself after the new declarative API is released.