\r\n vs \n in python eval function

eval, python

Solution

You have a strange definition of "work":

>>> eval("for i in range(5):\n print 'hello'")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    for i in range(5):
      ^
SyntaxError: invalid syntax
>>>

I'm not sure why you're using `eval` -- I suspect you mean `exec`. Expressions and statements are drastically different entities in Python -- `eval` only deals with expressions (a bare expression is also a statement, so `exec` can deal with it as well as other statements).

Turning to `exec`, and pondering the situation as a Python core committer, I think it's a minor mis-design: just like (redundant and useless) spaces, tabs and form feeds just before a NEWLINE are accepted and ignored, so should (just as redundant and useless) carriage returns be. I apologize: I think we never ever considered that somebody might want to put carriage returns there -- but then, it doesn't make any more sense to have e.g. form feeds there, and we do accept that... so I see no rationale for rejecting carriage returns (or other Unicode non-ANSI whitespace, either, now that in Python 3 we accept arbitrary Unicode non-ANSI alphanumerics in identifiers).

If you care, please open an issue on Python's issue tracker, and (barring unforeseen opposition by other commiters) I think I can get it fixed by Python 3.2 (which should be out in 12 to 18 months -- that's an estimate [informed guess], not a promise;-).

Problem

Why eval function doesn't work with \r\n but with \n. for example eval("for i in range(5):\r\n print 'hello'") doesn't work eval("for i in range(5):\n print 'hello'") works I know there is not a problem cause using replace("\r","") is corrected, but someone knows why happens? --Edit-- Oh! sorry , exactly, I meant exec. Carriage returns appeared because I'm reading from a HTML textarea via POST (I'm on a Linux box). now It is clearer, thanks to everyone.

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