Class: Binding
Relationships & Source Files | |
Inherits: | Object |
Defined in: | proc.c, prelude.rb |
Overview
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.
Instance Method Summary
-
#eval(string [, filename [,lineno]]) ⇒ Object
Evaluates the Ruby expression(s) in string, in the binding’s context.
-
#local_variable_defined?(symbol) ⇒ Object
Returns
true
if a local variablesymbol
exists. -
#local_variable_get(symbol) ⇒ Object
Returns the value of the local variable
symbol
. -
#local_variable_set(symbol, obj) ⇒ Object
Set local variable named
symbol
asobj
. -
#local_variables ⇒ Array
Returns the names of the binding’s local variables as symbols.
-
#receiver ⇒ Object
Returns the bound receiver of the binding object.
-
#source_location ⇒ Array, Integer
Returns the Ruby source filename and line number of the binding object.
- #force_activate(gem) private
- #clone Internal use only
- #dup Internal use only
-
#irb
(also: #irb)
Internal use only
Alias for #irb.
Instance Method Details
#clone
# File 'proc.c', line 316
static VALUE binding_clone(VALUE self) { VALUE bindval = binding_dup(self); return rb_obj_clone_setup(self, bindval, Qnil); }
#dup
# File 'proc.c', line 302
static VALUE binding_dup(VALUE self) { VALUE bindval = rb_binding_alloc(rb_cBinding); rb_binding_t *src, *dst; GetBindingPtr(self, src); GetBindingPtr(bindval, dst); rb_vm_block_copy(bindval, &dst->block, &src->block); RB_OBJ_WRITE(bindval, &dst->pathobj, src->pathobj); dst->first_lineno = src->first_lineno; return rb_obj_dup_setup(self, bindval); }
#eval(string [, filename [,lineno]]) ⇒ Object
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"
# File 'proc.c', line 396
static VALUE bind_eval(int argc, VALUE *argv, VALUE bindval) { VALUE args[4]; rb_scan_args(argc, argv, "12", &args[0], &args[2], &args[3]); args[1] = bindval; return rb_f_eval(argc+1, args, Qnil /* self will be searched in eval */); }
#force_activate(gem) (private)
[ GitHub ]# File 'prelude.rb', line 16
private def force_activate(gem) Bundler.reset! builder = Bundler::Dsl.new if Bundler.definition.gemfiles.empty? # bundler/inline Bundler.definition.locked_gems.specs.each{|spec| builder.gem spec.name, spec.version.to_s } else Bundler.definition.gemfiles.each{|gemfile| builder.eval_gemfile(gemfile) } end builder.gem gem definition = builder.to_definition(nil, true) definition.validate_runtime! begin orig_ui = Bundler.ui orig_no_lock = Bundler::Definition.no_lock ui = Bundler::UI::Shell.new ui.level = "silent" Bundler.ui = ui Bundler::Definition.no_lock = true Bundler::Runtime.new(nil, definition).setup rescue Bundler::GemNotFound warn "Failed to activate #{gem}, please install it with 'gem install #{gem}'" ensure Bundler.ui = orig_ui Bundler::Definition.no_lock = orig_no_lock end end
#irb Also known as: #irb
Alias for irb
.
# File 'prelude.rb', line 3
def irb begin require 'irb' rescue LoadError, Gem::LoadError force_activate 'irb' retry end irb end
#local_variable_defined?(symbol) ⇒ Object
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'")
# File 'proc.c', line 614
static VALUE bind_local_variable_defined_p(VALUE bindval, VALUE sym) { ID lid = check_local_id(bindval, &sym); const rb_binding_t *bind; const rb_env_t *env; if (!lid) return Qfalse; GetBindingPtr(bindval, bind); env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block)); return RBOOL(get_local_variable_ptr(&env, lid)); }
#local_variable_get(symbol) ⇒ Object
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}")
# File 'proc.c', line 521
static VALUE bind_local_variable_get(VALUE bindval, VALUE sym) { ID lid = check_local_id(bindval, &sym); const rb_binding_t *bind; const VALUE *ptr; const rb_env_t *env; if (!lid) goto undefined; GetBindingPtr(bindval, bind); env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block)); if ((ptr = get_local_variable_ptr(&env, lid)) != NULL) { return *ptr; } sym = ID2SYM(lid); undefined: rb_name_err_raise("local variable '%1$s' is not defined for %2$s", bindval, sym); UNREACHABLE_RETURN(Qundef); }
#local_variable_set(symbol, obj) ⇒ Object
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.
# File 'proc.c', line 570
static VALUE bind_local_variable_set(VALUE bindval, VALUE sym, VALUE val) { ID lid = check_local_id(bindval, &sym); rb_binding_t *bind; const VALUE *ptr; const rb_env_t *env; if (!lid) lid = rb_intern_str(sym); GetBindingPtr(bindval, bind); env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block)); if ((ptr = get_local_variable_ptr(&env, lid)) == NULL) { /* not found. create new env */ ptr = rb_binding_add_dynavars(bindval, bind, 1, &lid); env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block)); } #if YJIT_STATS rb_yjit_collect_binding_set(); #endif RB_OBJ_WRITE(env, ptr, val); return val; }
#local_variables ⇒ Array
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")
# File 'proc.c', line 493
static VALUE bind_local_variables(VALUE bindval) { const rb_binding_t *bind; const rb_env_t *env; GetBindingPtr(bindval, bind); env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block)); return rb_vm_env_local_variables(env); }
#receiver ⇒ Object
Returns the bound receiver of the binding object.
# File 'proc.c', line 634
static VALUE bind_receiver(VALUE bindval) { const rb_binding_t *bind; GetBindingPtr(bindval, bind); return vm_block_self(&bind->block); }
#source_location ⇒ Array, Integer
Returns the Ruby source filename and line number of the binding object.
# File 'proc.c', line 648
static VALUE bind_location(VALUE bindval) { VALUE loc[2]; const rb_binding_t *bind; GetBindingPtr(bindval, bind); loc[0] = pathobj_path(bind->pathobj); loc[1] = INT2FIX(bind->first_lineno); return rb_ary_new4(2, loc); }