Hi, I don't know if someone has already suggested this before, but here
goes:
With expressions allow using the enter/exit semantics of the with statement
inside an expression context. Examples:
contents = f.read() with open('file') as f #the most obvious one
multiplecontents = [f.read() with open(name) as f for name in names]
#reading multiple files
I don't know if it's worth making the "as NAME" part of the with mandatory
in an expression - is this a valid use case?
data = database.selectrows() with threadlock
Where this would benefit: I think the major use case is `f.read() with
open('file') as f`. Previous documentation has suggested
`open('file').read()` and rely on garbage collection; as the disadvantages
of that became obvious, it transitioned to a method that couldn't be done
in an expression:
with open('file') as f:
contents = f.read()
Therefore `f.read() with open('file') as f`, I think, would be much
welcomed as the best way to read a file in an expression.
For those wondering about the scope semantics of the "as NAME", I think
they would be identical to the scope semantics of the "for" expression -
i.e. these are legal:
contents = f.read() with open('file') as f
grid = [[i] * 4 for i in range(4)]
But these are not:
contents = f.read() with open('file') as f
f.seek(0)
grid = [[i] * 4 for i in range(4)]
grid[i][i] = 4
Is this a good idea? Are there some subtleties I've failed to explain?
Please let me know.
Sharing,
Ken Hilton
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