Object#instance_variable_defined?

obj.instance_variable_defined?(symbol) → true or false

obj.instance_variable_defined?(string) → true or false

static VALUE
rb_obj_ivar_defined(VALUE obj, VALUE iv)
{
    ID id = id_for_var(obj, iv, instance);

    if (!id) {
        return Qfalse;
    }
    return rb_ivar_defined(obj, id);
}

Returns true if the given instance variable is defined in obj. String arguments are converted to symbols.

Example

class Fred
  def initialize(p1, p2)
    @a, @b = p1, p2
  end
end
fred = Fred.new('cat', 99)
fred.instance_variable_defined?(:@a)    #=> true
fred.instance_variable_defined?("@b")   #=> true
fred.instance_variable_defined?("@c")   #=> false

See also #instance_of? #instance_variable_get #inspect #instance_variables also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0

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