Extend Interfaces and Existing R Types

[dereckmezquita]

Description

Allow interfaces to extend other interfaces or existing R types, similar to inheritance in object-oriented programming.

Related to #3

Implementation Ideas

• Modify the interface() function to accept a extends parameter.
• Update the check_interface() function to check properties from extended interfaces or types.
• Implement a mechanism to resolve property conflicts in case of multiple extensions.

Example Usage

# Extend an existing interface
Person <- interface("Person",
    name = "character",
    age = "numeric"
)

Employee <- interface("Employee",
    extends = Person,
    job_title = "character",
    salary = "numeric"
)

john <- implement(Employee,
    name = "John Doe",
    age = 30,
    job_title = "Developer",
    salary = 75000
)

# TODO: this needs more work
# Extend an existing R type
EnhancedDataFrame <- interface("EnhancedDataFrame",
    extends = "data.frame",
    metadata = "list"
)

my_df <- implement(EnhancedDataFrame,
    data.frame(x = 1:3, y = c("a", "b", "c")),
    metadata = list(created_at = Sys.time())
)

Integration with Existing Codebase

• Modify R/interface.R to handle the extends parameter.
• Update R/helpers.R to include extended property checking in check_interface().
• Add new test cases in tests/testthat/test-interface.R for extension functionality.