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Re: Question regarding the python binding

From: Роман Донченко <DXDragon_at_yandex.ru>
Date: Thu, 25 Mar 2010 18:56:26 +0300

Tino Schwarze <subversion.lists_at_tisc.de> писал в своём письме Thu, 25 Mar
2010 17:17:42 +0300:

> Hi there,
>
> Back to python: I managed to use the Python bindings to get a value from
> the config file (I didn't want to reinvent the wheel) like this:
>
> ***
> from svn import repos, fs, delta, core, client
>
> def main(pool, repos_dir):
>
> # for now, store client configuration in repository root
> cfgfile = repos_dir+'/conf/client.conf'
>
> svncfg = core.svn_config_read (cfgfile, True, pool)
>
> global_ignores = core.svn_config_get (svncfg,
> core.SVN_CONFIG_SECTION_GLOBAL, core.SVN_CONFIG_OPTION_GLOBAL_IGNORES,
> None)
>
> ***
>
> Now I'd like to verify our default set of required MIME types, so I need
> to get the contents of the [auto-props] section from the config file.
>
> libsvn provides the following function which should be suitable for my
> needs:
>
> svn_config_enumerate2(svn_config_t cfg, char section,
> svn_config_enumerator2_t callback, void baton, apr_pool_t pool) -> int
>
> Two questions arise:
>
> 1. How do I define an appropiate callback in Python? Looking at the SWIG
> documentation, I see examples on how to implement Python callbacks but
> they don't seem to match the current SVN bindings. I tried passing a
> Python method, deriving from svn_config_enumerator2_t etc. -> Segfault.

I took a look, and unfortunately this callback is not supported. The
reason for that is that SWIG can't automatically figure out how to call
Python callbacks, so a chunk of boring code must be written for each
callback type - and I guess no developers needed to scratch this
particular itch.

If it was supported, however, the call would look like this (and it *will*
look like this, after I become un-busy again and implement it):

def enumerator(name, value, pool):
   print "%s: %s" % (name, value)

core.svn_config_enumerate2(svncfg, core.SVN_CONFIG_SECTION_AUTO_PROPS,
enumerator)

> 2. What's the baton good for? Is it just some kind of additional data, I
> don't need to care about?

The baton argument is used up by the bindings themselves, you neither
should nor can supply your own (this applies to all callbacks).

> Maybe the devel list is more appropiate for such questions, but I wanted
> to try here first.

Not really, since this is a use question. 8=]

> Thanks,
>
> Tino.

Roman.
Received on 2010-03-25 16:57:16 CET

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