[Python-ideas] with statement syntax forces ugly line breaks? (original) (raw)
M.-A. Lemburg mal at egenix.com
Thu Sep 9 15:32:15 CEST 2010
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Mark Summerfield wrote:
Hi,
I can't see a nice way of splitting a with statement over mulitple lines: class FakeContext: def init(self, name): self.name = name def enter(self): print("enter", self.name) def exit(self, *args): print("exit", self.name) with FakeContext("a") as a, FakeContext("b") as b: pass # works fine
with FakeContext("a") as a, FakeContext("b") as b: pass # synax error with (FakeContext("a") as a, FakeContext("b") as b): pass # synax error The use case where this mattered to me was this: with open(args.actual, encoding="utf-8") as afh, open(args.expected, encoding="utf-8") as efh: actual = [line.rstrip("\n\r") for line in afh.readlines()] expected = [line.rstrip("\n\r") for line in efh.readlines()] Naturally, I could split the line in an ugly place: with open(args.actual, encoding="utf-8") as afh, open(args.expected, encoding="utf-8") as efh: but it seems a shame to do so. Or am I missing something?
Why do you need to put everything on one line ?
afh = open(args.actual, encoding="utf-8") efh = open(args.expected, encoding="utf-8")
with afh, efh: ...
In the context of files, the only purpose of the with statement is to close them when leaving the block.
a = open('/etc/passwd') b = open('/etc/group') with a,b: print a.readline(), b.readline() ... at:x:25:25:Batch jobs daemon:/var/spool/atjobs:/bin/bash at:!:25:
a <closed file '/etc/passwd', mode 'r' at 0x7f0093e62390> b <closed file '/etc/group', mode 'r' at 0x7f0093e62420>
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