Module | ActiveSupport::CachingTools::HashCaching |
In: |
lib/active_support/caching_tools.rb
|
Provide shortcuts to simply the creation of nested default hashes. This pattern is useful, common practice, and unsightly when done manually.
Dynamically create a nested hash structure used to cache calls to method_name The cache method is named +#{method_name}_cache+ unless :as => :alternate_name is given.
The hash structure is created using nested Hash.new. For example:
def slow_method(a, b) a ** b end
can be cached using hash_cache :slow_method, which will define the method slow_method_cache. We can then find the result of a ** b using:
slow_method_cache[a][b]
The hash structure returned by slow_method_cache would look like this:
Hash.new do |as, a| as[a] = Hash.new do |bs, b| bs[b] = slow_method(a, b) end end
The generated code is actually compressed onto a single line to maintain sensible backtrace signatures.