Re: [PATCH] Git.pm: Make File::Spec and File::Temp requirement lazy

["Bryan Donlan" <bdonlan@gmail.com>]

On Fri, Aug 15, 2008 at 11:10 AM, Marcus Griep <marcus@griep.us> wrote:
> This will ensure that the API at large is accessible to nearly
> all Perl versions, while only the temp file caching API is tied to
> the File::Temp and File::Spec modules being available.
>
> Signed-off-by: Marcus Griep <marcus@griep.us>
> ---
>
>  Eric Wong wrote:
>  > What about just lazy requiring inside _temp_cache() so it
>  > won't get loaded by folks that don't need it? (completely untested):
>  >
>  >              eval { require File::Temp };
>  >              if ($@) {
>  >                      throw Error::Simple("couldn't require File::Temp: $@");
>  >              }
>  >              eval { require File::Spec };
>  >              if ($@) {
>  >                      throw Error::Simple("couldn't require File::Spec: $@");
>  >              }
>  >
>  > It'll also remove the minor performance hit CGI/gitweb users got since
>  > we won't load these extra modules during startup.
>
>  This recommendation is implemented with this patch, but in such a way that only
>  the first test will be used, and that result cached.  That way we aren't doing
>  a compile _every_ time we want a temporary file, just the first time.

perl's 'require' will only attempt to load a module the first time it
is used; subsequent attempts will result in a quick no-op, so there's
no need to further cache. Unless you mean to cache a negative result?
In which case, the require should be quite fast, as it'll quickly get
a 'file not found' error without needing to do any compilation.