Equivalent of “pass” in Ruby

nil is probably the equivalent of it:

def some_function
    nil
end

It's basically helpful when ignoring exceptions using a simple one-line statement:

Process.kill('CONT', pid) rescue nil

Instead of using a block:

begin
    Process.kill('CONT')
rescue
end

And dropping nil would cause syntax error:

> throw :x rescue
SyntaxError: (irb):19: syntax error, unexpected end-of-input
        from /usr/bin/irb:11:in `<main>'

Notes:

def some_function; end; some_function returns nil.

def a; :b; begin; throw :x; rescue; end; end; a; also returns nil.

You always have end statements, so pass is not needed.

Ruby example:

def some_function()
    # do nothing
end

Ruby 3.0

As of Ruby 3.0, so-called "endless" method definitions are now supported -- we no longer require end statements with every single method definition. This means the most concise way of expressing an empty method like the example above is now arguably something like this:

def some_function = nil

Alternatively, there has always been an uglier one-line option using the much-hated semicolon:

def some_function; end

Note that this doesn't really change anything about the first solution except how the code can be written.

No, there is no such thing in Ruby. If you want an empty block, method, module, class etc., just write an empty block:

def some_method
end

That's it.

In Python, every block is required to contain at least one statement, that's why you need a "fake" no-op statement. Ruby doesn't have statements, it only has expressions, and it is perfectly legal for a block to contain zero expressions.