class Binding

Objects of class Binding encapsulate the execution context at some particular place in the code and retain this context for future use. The variables, methods, value of self, and possibly an iterator block that can be accessed in this context are all retained. Binding objects can be created using Kernel#binding, and are made available to the callback of Kernel#set_trace_func and instances of TracePoint.

These binding objects can be passed as the second argument of the Kernel#eval method, establishing an environment for the evaluation.

class Demo
  def initialize(n)
    @secret = n
  end
  def get_binding
    binding
  end
end

k1 = Demo.new(99)
b1 = k1.get_binding
k2 = Demo.new(-3)
b2 = k2.get_binding

eval("@secret", b1)   #=> 99
eval("@secret", b2)   #=> -3
eval("@secret")       #=> nil

Binding objects have no class-specific methods.

Public Instance Methods

clone

() → self

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 33
def clone: () -> self

eval

(string src, ?string filename, ?int lineno) → untyped

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 49
def eval: (string src, ?string filename, ?int lineno) -> untyped

Evaluates the Ruby expression(s) in string, in the binding‘s context. If the optional filename and lineno parameters are present, they will be used when reporting syntax errors.

def get_binding(param)
  binding
end
b = get_binding("hello")
b.eval("param")   #=> "hello"

local_variable_defined?

(interned varname) → bool

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 67
def local_variable_defined?: (interned varname) -> bool

Returns true if a local variable symbol exists.

def foo
  a = 1
  binding.local_variable_defined?(:a) #=> true
  binding.local_variable_defined?(:b) #=> false
end

This method is the short version of the following code:

binding.eval("defined?(#{symbol}) == 'local-variable'")

local_variable_get

(interned varname) → untyped

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 85
def local_variable_get: (interned varname) -> untyped

Returns the value of the local variable symbol.

def foo
  a = 1
  binding.local_variable_get(:a) #=> 1
  binding.local_variable_get(:b) #=> NameError
end

This method is the short version of the following code:

binding.eval("#{symbol}")

local_variable_set

[U] (interned varname, U obj) → U

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 112
def local_variable_set: [U] (interned varname, U obj) -> U

Set local variable named symbol as obj.

def foo
  a = 1
  bind = binding
  bind.local_variable_set(:a, 2) # set existing local variable `a'
  bind.local_variable_set(:b, 3) # create new local variable `b'
                                 # `b' exists only in binding

  p bind.local_variable_get(:a)  #=> 2
  p bind.local_variable_get(:b)  #=> 3
  p a                            #=> 2
  p b                            #=> NameError
end

This method behaves similarly to the following code:

binding.eval("#{symbol} = #{obj}")

if obj can be dumped in Ruby code.

local_variables

() → Array[Symbol]

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 131
def local_variables: () -> Array[Symbol]

Returns the names of the binding’s local variables as symbols.

def foo
  a = 1
  2.times do |n|
    binding.local_variables #=> [:a, :n]
  end
end

This method is the short version of the following code:

binding.eval("local_variables")

receiver

() → untyped

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 139
def receiver: () -> untyped

Returns the bound receiver of the binding object.

source_location

() → [ String, Integer ]

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/core/binding.rbs, line 147
def source_location: () -> [String, Integer]

Returns the Ruby source filename and line number of the binding object.