# Introspection(and its alternatives) in Crystal
**URL:** https://forum.crystal-lang.org/t/introspection-and-its-alternatives-in-crystal/5536
**Category:** Help & Support
**Created:** [April 3, 2023, 10:53pm UTC](https://forum.crystal-lang.org/t/introspection-and-its-alternatives-in-crystal/5536 "2023-04-03T22:53:39Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@ch1c0t](https://forum.crystal-lang.org/u/ch1c0t)
#### Post date: [April 3, 2023, 10:53pm UTC](https://forum.crystal-lang.org/t/introspection-and-its-alternatives-in-crystal/5536/1 "2023-04-03T22:53:39Z")
In Ruby, it is very helpful to use introspection methods(like `#constants`) to discover new APIs.
By analogy, I tried the same in Crystal, with [this example](https://github.com/jhass/crystal-gobject/blob/1e299838bc9c0112a5a16f57021fafd3e31f031d/samples/gtk_accel_group.cr):
```crystal
require "gobject/gtk/autorun"
window = Gtk::ApplicationWindow.new(title: "AccelGroup", border_width: 20)
window.connect "destroy", ->Gtk.main_quit
window.add Gtk::Label.new("Press Ctrl+S")
accel_group = Gtk::AccelGroup.new
accel_group.connect(Gdk::KEY_S, :control_mask, :zero_none) do
puts "Ctrl+S pressed!"
end
window.add_accel_group(accel_group)
p! Gdk.constants
window.show_all
```
But it failed to compile with:
```auto
| p! Gdk.constants
^--------
Error: undefined method 'constants' for Gdk:Module
```
I intended to find out what other combinations besides Ctrl+S(`Gdk::KEY_S`) are there.
I wonder, in similar situations, what do you use for introspection in Crystal?
---
### Author:  [@Blacksmoke16](https://forum.crystal-lang.org/u/Blacksmoke16)
#### Post date: [April 4, 2023, 12:11am UTC](https://forum.crystal-lang.org/t/introspection-and-its-alternatives-in-crystal/5536/2 "2023-04-04T00:11:13Z")
There still is introspection, but it’s not available at runtime. You could try like `{% pp Gdk.constants %}`. Although the more conventional way to do it (maybe not applicable in this context) is to leverage the generated API docs. This gives you something like [Crystal 1.8.0-dev](https://crystal-lang.org/api/master/index.html), but for a particular project. These are ideally hosted by the shard to make it easy to explore. However given this particular shard relates to generating bindings to C libs, your best bet would be finding the docs for that lib. E.g. [Gdk – 3.0](https://docs.gtk.org/gdk3/index.html#constants).
EDIT: One thing to keep in mind is `.constants` will include both actual constants and types within that namespace.
Somewhat related: [Print out the instance methods defined class? or the path where the current class is?](https://forum.crystal-lang.org/t/print-out-the-instance-methods-defined-class-or-the-path-where-the-current-class-is/4771)
---
### Author:  [@ch1c0t](https://forum.crystal-lang.org/u/ch1c0t)
#### Post date: [April 4, 2023, 2:07am UTC](https://forum.crystal-lang.org/t/introspection-and-its-alternatives-in-crystal/5536/3 "2023-04-04T02:07:03Z")
Thank you!