This tells Smarty whether or not to cache the output of the templates.
By default this is set to 0, or disabled. If your templates generate
redundant redundant content, it is advisable to turn on caching. This
will result in significant performance gains. You can also have multiple
caches for the same template. A value of 1 or 2 enables caching. 1 tells
Smarty to use the current $cache_lifetime variable to determine if the
cache has expired. A value of 2 tells Smarty to use the cache_lifetime
value at the time the cache was generated. This way you can set the
cache_lifetime just before fetching the template to have granular
control over when that particular cache expires. See also is_cached.
告诉Smarty是否缓存模板的输出.默认情况下,她设为0,或无效.如果模板产生冗余内容,建议打开缓存.这样有利于获得良好的性能增益.你也可以为同一模板设有多个缓存.当值为1或2时启动缓存.1告诉Smarty
使用当前的$cache_lifetime变量判断缓存是否过期.2告诉 Smarty
使用生成缓存时的cache_lifetime值.用这种方式你正好可以在获取模板之前设置缓存生存时间，以便较精确地控制缓存何时失效.
If $compile_check is enabled, the cached content will be regenerated if
any of the templates or config files that are part of this cache are
changed. If $force_compile is enabled, the cached content will always be
regenerated.
如果启动了编译检查,一旦任何的模板文件或配置文件(有关缓存部分的配置文件)被修改,缓存的内容将会重新生成.如果启动了强迫编译,缓存的内容将总会重新生成.