Replace __file__ with newer APIs

[jayvdb]

#533 replaced custom data lookup with __file__, which works only if the resources are exported to a filesystem. See indygreg/PyOxidizer#69 for more info about why, but the tl;dr version is __file__ is an optional attribute and should not be relied upon. It also requires each zip/pack tool to fiddle with __file__.

Here is the current backtrace when __file__ is not provided:

  File "babel", line 20, in <module>
    from babel.core import UnknownLocaleError, Locale, default_locale, \
  File "babel.core", line 14, in <module>
    from babel import localedata
  File "babel.localedata", line 24, in <module>
    _dirname = os.path.join(os.path.dirname(__file__), 'locale-data')
NameError: name '__file__' is not defined

There are stdlib APIs for this type of access, especially the now ancient pkgutil.get_data, and the newer importlib.resources and backport importlib_resources.

Loading of resources from the runtime package should ideally be done using importlib.resources and its backport , however pkgutil could be used to avoid the need for the backport. Using pkgutil doesn't work under PyOxidizer 0.4, however I expect that will be fixed soon.

[akx]

#533 is actually not to "blame" here – the package has been using __file__ to locate locale data since forever (13 years ago and counting – I didn't feel like clicking back through blames further than that).

I wouldn't mind a patch that has Babel attempt to use, say, importlib.resources.open_binary() when available and fall back to the current __file__ behavior, but more drastic changes would have to be Babel 3.x+ (see #569) and probably related to the vaguely discussed custom loader stuff (#454 (comment)).

[jayvdb]

Apologies for seeming to allocate blame. I was trying to say that #533 brought Babel to the point that tools which uses __file__ hacks, like PyInstaller, would work reliably, but the next step is to also work with tools which rely on stdlib.

I wouldn't mind a patch that has Babel attempt to use, say, importlib.resources.open_binary() when available and fall back to the current __file__ behavior

That should be sufficient. I'll try it.

[akx]

Apologies for seeming to allocate blame.

I didn't mean it like that – let me explain:

I was trying to say that #533 brought Babel to the point that tools which uses __file__ hacks, like PyInstaller, would work reliably, but the next step is to also work with tools which rely on stdlib.

#533 reverted some changes to that directory code that had been ultimately unnecessary; PyInstaller had had __file__ hacks/fixups for Babel since time immemorial, and Babel itself has used the same pattern using __file__ since 1.0 and probably before it.

That should be sufficient. I'll try it.

Come to think of it, if importlib.resources doesn't have an API to iterate over resources of a certain kind, that may be a bit of a hurdle. The code for enumerating locales needs that.