Using REPL

Open the REPL, type 1 + 1 and press Ctrl-Enter.

The result will be displayed.

The REPL supports several shortcuts.

• Ctrl-u clears the input field
• Ctrl-k deletes text after the cursor in the input field
• Ctrl-l clears the output field
• Up arrow (↑), Down arrow (↓) navigates through input field history
• Ctrl-[ switches to the Editor tab
• Ctrl-] switches back to the REPL tab

The REPL also supports multi-line input, with Enter as a newline.

Type the following and press Ctrl-Enter.

class Foo
  def bar
    'FooBar'
  end
end

Foo.new.bar

Output

=> "FooBar"

Emit signals

Try each of the following:

foo 'bar'

Godot.emit_signal :foo, 'bar'

Output

[ foo ] method_missing: ["bar"]
=> <null>

[ foo ] signal emitted: "bar"
=> true

=> represents the return value of the method. If any signal is emitted, it will be displayed in the output.

Red text is displayed when a method_missing channel signal is emitted, while blue text appears when a channel signal is emitted.

Define methods

Try the following:

@count = 0
def up
  @count += 1
end

Then, try up a few times.

Output

up
=> 1
up
=> 2
up
=> 3

100.times { up }
@count

Output

100.times { up }
=> 100
@count
=> 104

caution

Local variables are no longer available after execution. So use instance variables like @count = 0 instead of count = 0.

Use require

mruby doesn't include require by default, but ReDScribe provides it as a helper method that loads Ruby files from the root of your Godot project.

require 'addons/redscribe/mrblib/math'

Run this, if the file loads successfully, it will return true. The file is only loaded once—on subsequent calls, it will return false.

Output

=> true

After executing require, try calling:

sin(1)

Output

=> 0.8414709848079

addons/redscribe/mrblib/math.rb calls extend Math, making the sin method available.

addons/redscribe/mrblib/math.rb

extend Math
include Math

def π
  PI
end

def √(x)
  sqrt(x)
end

# ...

Reload and initialze the REPL

To initialize the REPL, run:

reload!

Once initalized, if you call the up or sin method again, you'll get method_missing.

up
sin(1)

Output

[ up ] method_missing: []
[ sin ] method_missing: [1]
=> <null>

That's the basic usage of the REPL.

The REPL can be very helpful—feel free to use it whenever you like!