On 12:56 pm, ncogh...@gmail.com wrote:
PEP 377 is a proposal to allow context manager __enter__() methods to
skip the body of the with statement by raising a specific (new) flow
control exception.
Since there is a working reference implementation now, I thought it was
time to open it up for broader discussion.
Why not allow a context manager to implement some other method, for the
sake of argument let's say "__start__", which was invoked with a
callable object and could choose to evaluate or not evaluate the
statement body by simply not calling that object (or perhaps iterable,
in the case of a generator)?
This PEP proposes that we have two ways to deal with the body of a
'with' statement: either the body is run or not. I have always wanted
to have another option: run the body later.
Passing around an object representing the body of the with statement
would allow for this use-case, as well as removing the ugly protrusion
of yet another control-flow exception (which, as has already been noted,
creates difficulties for some other python implementations).
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