[Templates] PROPOSAL: Allow CACHE_STR_REFS configuration item

[Paul Seamons]

Because of the way Text::Tmpl functions, it must operate on filenames.
Therefore any stringref that is parsed is first saved to a file using
the md5 sum of the string.  While writing to file isn't the best thing,
using the md5 sum is actually a performance improvement.

Template::Alloy provides the CACHE_STR_REFS configuration item which
defaults to true.  It allows for stringrefs to use the same caching
mechanisms as normal files (both in memory and/or to filesystem).
It also works for eval'ed strings.

Taking the md5 sum is far less costly then parsing and evaluating the
string ref each time (the md5 sum method is 2-3 times faster in most
cases).

Some sample benchmark output can be found at the following url (the relevant 
cases here would be TA_NOCACHE and TA under the string ref section):

http://search.cpan.org/~rhandom/Template-Alloy-1.002/samples/benchmark/bench_various_templaters.pl

Setting CACHE_STR_REFS to 0 would disable stringref caching.

This item probably could be added to TT2 without too much invasion,
though a code analysis hasn't been performed.

If implemented, passing in stringrefs or evaling strings can avoid
the penalty of parsing every time.

Paul Seamons