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instance method

Binding#local_variable_defined?

(::interned varname) -> bool

binding.local_variable_defined?(symbol) → obj

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;
    if (rb_numparam_id_p(lid)) {
        rb_name_err_raise("numbered parameter '%1$s' is not a local variable",
                          bindval, ID2SYM(lid));
    }

    GetBindingPtr(bindval, bind);
    env = VM_ENV_ENVVAL_PTR(vm_block_ep(&bind->block));
    return RBOOL(get_local_variable_ptr(&env, lid, TRUE));
}

Returns true if a local variable symbol exists.

Example

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:

Example

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

Ruby version changes

4.0
- Binding#local_variables does no longer include numbered parameters. Also, Binding#local_variable_get, Binding#local_variable_set, and Binding#local_variable_defined? reject to handle numbered parameters. [Bug #21049]

See also #implicit_parameters #local_variable_get #implicit_parameter_get #local_variables also in 4.0 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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