of the resources being allocated of the processing.It is very common though to wrap the `with block` in an outer `try` block, since although we know that the resource has been closed, at an 'application' level it is still neccessary
to deal with the exception - an example might be :
try:
with open('config.cfg', 'r') as cfg:
# Process the open file
config = load_config(cfg)
except FileNotFound:
logging.info('Config file not found - using default configuration')
except PermissionError:
logging.warning('Cannot open config .cfg - using default configuration')
config = default_config()
else:
logging.info('Using config from config.cfg')
It struck me that this is probably quite a common idiom, and we have the
main processing (of the opened resources) indented twice just to accommodate
the outer try block.I was wondering whether a worthwhile extension might be to allow the `with` statement to have an `except` and `else` clauses which would have the same semantics as wrapping the `with` block with a try - for example the above would now look like:
with open('config.cfg', 'r') as cfg:
# Process the open file
config = load_config(cfg)
except FileNotFound:
logging.info('Config file not found - using default configuration')
except PermissionError:
logging.warning('Cannot open config .cfg - using default
configuration')
config = default_config()
else:
logging.info('Using config from config.cfg')
Treating the 'with' as an implied `try` would reduce the march to the
right - now the key processing of the resource is now indented only one
level - and the association of the exception
from the `with` block is syntactically clear.I am not good enough with core development to put together a working prototype, but I can imagine that this simple extension would be worth while, but I would be more than happy to author a PEP for this if it gets some initial positive feedback.
Open questions - that I have - should we allow `except`, `else` and `finally` clauses (or just `except` and `else` - do we need `finally` here).
-- Anthony Flury *Moble*: +44 07743 282707 *Home*: +44 (0)1206 391294 *email*: anthony.fl...@btinternet.com <mailto:anthony.fl...@btinternet.com>
<<attachment: anthony_flury.vcf>>
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