我一直在使用xDebug运行一些代码，并且经常将_underscoreCache注意为k对的数组：
object
collection
is_default
default_group_id
front
store_id
action
session_hosts
controller_action
request
secure
visitor_data
website
quote
items_collection
parent_item_id
quote_id
item_id
product_id
code
attributes
website_id
attribute_set_id
additional_attribute_table
attribute_codes
is_global
skip_confirmation_if_email
confirmation
visibility
is_salable
stock_item
udropship_vendor
custom_vars_combined
password_enc
vendor_name
use_local_stock
is_recurring
customer_group_id
date
product_collection
product_name
product_type_id
product_status_changed
is_changed_websites
product_changed_websites
license_key
license_key
license_status
license_expire
server_restriction
products
module_name
use_config_manage_stock
is_in_stock
stock_status
product_type
sku
name
weight
tax_class_id
cost
base_cost
is_qty_decimal
quote_item
product
message
item
is_super_mode
qty_to_add
is_child_item
has_error
item_is_qty_decimal
has_qty_option_update
item_qty
orig_qty
use_config_min_sale_qty
use_config_max_sale_qty
suppress_check_qty_increments
use_config_enable_qty_increments
use_config_min_qty
item_use_old_qty
item_backorders
ignore_old_qty
use_old_qty
skip_check_required_option
ud_skip_quote_load_after_event
order
has_children
vendor_sku
address_type
address
postcode
limit_zipcode
country_id
allowed_countries
stockcheck_method
true_stock
udropship_stock_levels
stock_result
quote_currency_code
currency_code
customer_id
prefix
customer_prefix
firstname
customer_firstname
middlename
customer_middlename
lastname
customer_lastname
suffix
customer_suffix
email
customer_email
dob
customer_dob
taxvat
customer_taxvat
gender
customer_gender
customer_tax_class_id
remote_ip
x_forwarded_for
items_count
checkout_method
checkout_state
collect_shipping_rates
totals_collected_flag
extra_tax_amount
base_extra_tax_amount
subtotal
base_subtotal
subtotal_with_discount
base_subtotal_with_discount
grand_total
base_grand_total
quote_address
is_multi_shipping
total_qty
base_virtual_amount
virtual_amount
subtotal_incl_tax
base_subtotal_incl_tax
applied_rule_ids
shipping_tax_amount
base_shipping_tax_amount
applied_taxes_reset
free_shipping
free_method_weight
region_id
customer_class_id
store
parent_id
product_class_id
shipping_amount
base_shipping_amount
shipping_incl_tax
base_shipping_incl_tax
shipping_taxable
base_shipping_taxable
is_shipping_incl_tax
base_cod_fee
cod_fee
cod_tax_amount
base_cod_tax_amount
method
prev_quote_customer_group_id
discount_amount
base_discount_amount
base_calculation_price
calculation_price
base_original_price
original_custom_price
rate
row_total
base_row_total
coupon_code
no_discount
coupon_type
uses_per_customer
is_primary
uses_per_coupon
use_auto_generation
usage_limit
operator_option
operator_by_input_type
value_option
operator_options
type
aggregator
value
actions
aggregator_option
aggregator_options
rule
conditions_serialized
attribute_option
attribute
operator
is_value_parsed
value_parsed
actions_serialized
simple_free_shipping
stop_rules_processing
tax_percent
custom_price
base_price
price_incl_tax
base_price_incl_tax
row_total_incl_tax
base_row_total_incl_tax
taxable_amount
base_taxable_amount
is_price_incl_tax
rounding_deltas
weee_tax_applied
base_weee_tax_disposition
weee_tax_disposition
base_weee_tax_row_disposition
weee_tax_row_disposition
base_weee_tax_applied_amount
base_weee_tax_applied_row_amount
weee_tax_applied_amount
weee_tax_applied_row_amount
row_weight
all_items
dest_country_id
dest_region_id
dest_region_code
dest_street
city
dest_city
dest_postcode
package_value
package_value_with_discount
package_weight
package_qty
package_physical_value
base_currency
package_currency
limit_carrier
orig
path
cipher
mode
handler
init_vector
active_flag
error
weight_type
full_row_weight
carrier_code
zip
ups_pickup
ups_container
ups_dest_type
udropship_calculate_rates
calculate_rates_by_group_flag
requests
website_ids
system_methods
答案 0 :(得分：11)
简短版本：如果您不知道这是为了什么，则无需使用它。
长版本。
这与underscoe.js毫无关系。在它是一个javascript框架之前，下划线是一个简单的ASCII字符_。
在Magento的系统中，大多数对象都是从基础
继承的Varien_Object
类。该对象为Magento的对象提供了特殊功能。例如，在Magento对象中，您不需要定义setter和getter。你可以做这样的事情
$object = new SomeObject; //which inherits form Varien_Object
$object->setSomeValue('Our Value');
echo $object->getSomeValue('Our Value');
echo $object->getData('our_value');
$data = $object->getData();
echo $data['our_value'];
在上面的示例中，没有名为setSomeValue的具体方法。 Magento神奇地知道我们只想设置数据属性。这是在PHP魔术方法__call
#File: lib/Varien/Object.php
public function __call($method, $args)
{
...
}
当您调用setSomeValue时，Magento会在名为some_value的对象数据数组上设置一个键。也就是说，它需要将驼峰式SomeValue转换为非驼峰式some_value。您可以在此处的魔术__call实施中看到
#File: lib/Varien/Object.php
public function __call($method, $args)
{
case 'set' :
//Varien_Profiler::start('SETTER: '.get_class($this).'::'.$method);
$key = $this->_underscore(substr($method,3));
$result = $this->setData($key, isset($args[0]) ? $args[0] : null);
//Varien_Profiler::stop('SETTER: '.get_class($this).'::'.$method);
return $result;
}
_underscore方法接受字符串SomeValue，并使用以下行将其转换为some_value
#File: lib/Varien/Object.php
$result = strtolower(preg_replace('/(.)([A-Z])/', "$1_$2", $name));
在某些时候，无论是通过剖析还是直觉，Magento开发人员都意识到每次数据被获取或设置在一个对象上时调用strToLower和preg_replace 意味着一个性能瓶-颈部。为了解决这个问题，他们引入了_underscoeCache。这是一个数组，以及Varien_Object类
#File: lib/Varien/Object.php
/**
* Setter/Getter underscore transformation cache
*
* @var array
*/
protected static $_underscoreCache = array();
如果查看整个_underscore方法，可以看到它是如何使用的
protected function _underscore($name)
{
if (isset(self::$_underscoreCache[$name])) {
return self::$_underscoreCache[$name];
}
#Varien_Profiler::start('underscore');
$result = strtolower(preg_replace('/(.)([A-Z])/', "$1_$2", $name));
#Varien_Profiler::stop('underscore');
self::$_underscoreCache[$name] = $result;
return $result;
}
也就是说，Magento仍将执行strToLower和preg_replace转换，但每个唯一字符串只执行一次。完成后，键/值（SomeValue和some_value）将放置在_underscoreCache
self::$_underscoreCache[$name] = $result;
这样，下次调用该方法时，将返回缓存中的值
if (isset(self::$_underscoreCache[$name])) {
return self::$_underscoreCache[$name];
}
这样可以避免对常用引用变量调用strToLower和preg_replace。
答案 1 :(得分：0)
完美的澄清，但我可以'从前端夯实系统中取出一个变量。 即使我在$ _underscoreCache
中看到了它我用：
Mage::getSingleton('core/session')->getCartWasUpdated();
我想采取在中设置的var cartControlller.php
$this->_getSession()->setCartWasUpdated(true);