[Python-Dev] eval and triple quoted strings (original) (raw)

Guido van Rossum guido at python.org
Tue Jun 18 00:35:12 CEST 2013

On Mon, Jun 17, 2013 at 3:18 PM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

Guido van Rossum wrote:

No. Executing a file containing those exact characters produces a string containing only '\n' and exec/eval is meant to behave the same way. The string may not have originated from a file, so the universal newlines behavior of the io module is irrelevant here -- the parser must implement its own equivalent processing, and it does.

I'm still not convinced that this is necessary or desirable behaviour. I can understand the parser doing this as a workaround before we had universal newlines, but now that we do, I'd expect any Python string to already have newlines converted to their canonical representation, and that any CRs it contains are meant to be there. The parser shouldn't need to do newline translation a second time.

There are other ways to get a string besides reading it from a file.

Anyway, I think that if you want a string literal that contains \r\n as its line endings, you should use a syntactic solution, and the syntax ought to be the same regardless of whether you are reading it from a file or from a string literal. That syntactic solution is very clear:

"""line one\r line two\r line three\r """

This works everywhere.

-- --Guido van Rossum (python.org/~guido)

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