On 24/07/2014 6:48 pm, Brett Cannon wrote:
On Thu Jul 24 2014 at 1:07:12 PM, Phil Thompson
<p...@riverbankcomputing.com>
wrote:
I have an importer for use in applications that embed an interpreter
that does a similar job to the Zip importer (except that the storage
is
a C data structure rather than a .zip file). Just like the Zip
importer
I need to import my importer and add it to sys.path_hooks. However the
earliest opportunity I have to do this is after the Py_Initialize()
call
returns - but this is too late because some parts of the standard
library have already needed to be imported.
My current workaround is to include a modified version of
_bootstrap.py
as a frozen module that has the necessary steps added to the end of
its
_install() function.
The Zip importer doesn't have this problem because it gets special
treatment - the call to its equivalent code is hard-coded and happens
exactly when needed.
What would help is a table of functions that were called where
_PyImportZip_Init() is currently called. By default the only entry in
the table would be _PyImportZip_Init. There would be a way of
modifying
the table, either like how PyImport_FrozenModules is handled or how
Inittab is handled.
...or if there is a better solution that I have missed that doesn't
require a modified _bootstrap.py.
Basically you want a way to specify arguments into
importlib._bootstrap._install() so that sys.path_hooks and
sys.meta_path
were configurable instead of hard-coded (it could also be done just
past
importlib being installed, but that's a minor detail). Either way there
is
technically no reason not to allow for it, just lack of motivation
since
this would only come up for people who embed the interpreter AND have a
custom importer which affects loading the stdlib as well (any reason
you
can't freeze the stdblib as a solution?).
Not really. I'd lose the compression my importer implements.
(Are there any problems with freezing packages rather than simple
modules?)
We could go the route of some static array that people could modify.
Another option would be to allow for the specification of a single
function
which is called just prior to importing the rest of the stdlib,
The problem with all of this is you are essentially asking for a hook
to
let you have code have access to the interpreter state before it is
fully
initialized. Zipimport and the various bits of code that get loaded
during
startup are special since they are coded to avoid touching anything
that
isn't ready to be used. So if we expose something that allows access
prior
to full initialization it would have to be documented as having no
guarantees of interpreter state, etc. so we are not held to some API
that
makes future improvements difficult.
IOW allowing for easy patching of Python is probably the best option I
can
think of. Would tweaking importlib._bootstrap._install() to accept
specified values for sys.meta_path and sys.path_hooks be enough so that
you
can change the call site for those functions?
My importer runs under PathFinder so it needs sys.path as well (and
doesn't need sys.meta_path).
Phil
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