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[Python-Dev] Backporting PEP 414
Nick Coghlanncoghlan at gmail.com
Wed Feb 29 00:25:52 CET 2012
On Wed, Feb 29, 2012 at 8:17 AM, Chris McDonough <chrism at plope.com> wrote:> But yeah. A year from now I wouldn't remember which version of 3.2 got> a new feature, and neither would anybody else. The no-new-features> guidelines are useful in the real world this way, because they represent> a coherent policy, as tempting as it is to just jam it in.Also, I think there may be some confusion about Armin's plan to handle3.2 - he aims to write an *import hook* that accepts the u/U prefixesduring tokenisation, not a source-to-source transform like 2to3. It'sclumsier than the plan for native syntactic support in 3.3 (sinceyou'll need to make sure the import hook is installed, the presence ofthe hook will add overhead during application startup, and anyattempts to compile affected modules that don't go through the importmachinery will fail with a syntax error), but the presence ofimportlib in 3.2 makes it quite feasible. When loading from a cached.pyc, the hook won't even have to do anything special (since thetokenisation change only affects the compilation step).Assuming Armin can get the hook working as intended, then long runningapplications where startup overhead isn't a big deal will just need toensure the hook is in place before they import any modules that usethe old-style string literals. For cases where the startup overheadisn't acceptable (such as command line applications), then approachesthat change the source in advance (i.e. separate branches or singlesource with the unicode_literals future import) will continue to bethe preferred mechanism for providing 3.2 support.Cheers,Nick.-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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