Introspection

Easy introspection for the Crystal language.

The Crystal language provides introspection (type reflection) through the use of macros. This shard contains easy methods for getting the type information without macros.

If you want to use type introspection information to modify the code of your Crystal program, you'll still have to do it the macro way, not using this shard.

Currently this shard only provides an Object#instance_methods method. This works on instances, classes, and modules. It returns the data structure below.

For a discussion of internal and external argument names, please see this section of the Crystal documentation.

[   # This is an array of named tuples defining methods.
  {
    visibility : String, # "public", "private", "protected".
    name : String, # Name of the method.
    double_splat : String # Name of the double-splat argument, if present.
    splat_index : Int32 # Argument number of the double-splat argument.
    return_type : String # The return type of the method.
    arguments : [ # Array of arguments to the method.
      {
        name : String # The argument's external name.
        internal_name : String # The argument's internal name.
        type : String # The type restriction of the argument.
        default_value : String # The default value, if no argument is provided.
      },
    ]
    block_arguments : [
        String, ... # The types of the block arguments.
    ],
    block_return : String # The return type of the block.
    body : String # The text of the method body.
  },
]

Usage

This program gets an array of information about the instance methods of Object. It selects the information for Object#pretty_inspect, and then renders that information using Object#pretty_inspect.

require "introspection"

puts Object.instance_methods.find { |method| method[:name] == "pretty_inspect" }.pretty_inspect

It should print something like:

{visibility: ":public",
 name: "pretty_inspect",
 double_splat: "",
 splat_index: 0,
 return_type: "String",
 arguments: 
  [{name: "width", internal_name: "width", type: "", default_value: "79"},
   {name: "newline",
    internal_name: "newline",
    type: "",
    default_value: "\"\\n\""},
   {name: "indent", internal_name: "indent", type: "", default_value: "0"}],
 block_argument: [],
 block_return: "",
 body: 
  "String.build do |io|\n" +
  "  PrettyPrint.format(self, io, width, newline, indent)\n" +
  "end"}

Installation

Add the dependency to your shard.yml:

dependencies:
  introspection:
    github: BrucePerens/introspection

Run shards install

TODO: Write usage instructions here

Development

TODO: Write development instructions here

Contributing

Fork it (https://github.com/your-github-user/introspection/fork)
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

Contributors

[Bruce Perens](bruce@perens.com, @BrucePerens, https://github.com/BrucePerens) - creator and maintainer.