Message285902
In its current implementation, `ConfigParser` calls its Interpolation's `before_read` method in the very last step of `_read`, when all properties have already been overwritten by their new uninterpolated values.
I am developing a program with modular config files: It is possible to supply several configuration files on the command line, and they are all fed through the `.read` method.
Now it would be amazing to use `read` time interpolation instead of `get` time interpolation to construct things like
outputfilename = %(outputfilename)s_extension_from_this_ini_module
By looking at the `Interpolation` class, it seems that behaviour like this should be supported by supplying a `before_read` as follows.
def before_read(self, parser, section, option, value):
L = []
interpolations = parser[section]
self._interpolate_some(
parser, option, L, value, section, interpolations, 1)
return ''.join(L)
However, this is not possible, because `before_read` is only called *after* all values in the config file have been read and all old values in the ConfigParser object have been overridden.
The attached file contains a subclass of `BasicInterpolation` and a subclass of `ConfigParser` which in concert allow me to write recursive property definitions as given above.
The downside of this change is that (a) interpolation values can't be defined *after* they are used any more, and (b) it is not possible to hack this parser to accept multi-line option names as interpolations. (To me personally, both of these don't sound like useful features to begin with.) |
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Date |
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Action |
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2017-01-20 11:50:36 | Anaphory | set | recipients:
+ Anaphory |
2017-01-20 11:50:36 | Anaphory | set | messageid: <1484913036.08.0.781257093151.issue29333@psf.upfronthosting.co.za> |
2017-01-20 11:50:36 | Anaphory | link | issue29333 messages |
2017-01-20 11:50:35 | Anaphory | create | |
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