[Python-Dev] [python] Re: New lines, carriage returns, and Windows

[Michael Foord]

Steve Holden wrote:
> Michael Foord wrote:
>   
>> Steven Bethard wrote:
>>     
>>> On 9/29/07, Michael Foord <fuzzyman at voidspace.org.uk> wrote:
>>>   
>>>       
>>>> Terry Reedy wrote:
>>>>     
>>>>         
>>>>> There are two normal ways for internal Python text to have \r\n:
>>>>> 1. Read from a file with \r\r\n.  Then \r\r\n is correct output (on the
>>>>> same platform).
>>>>> 2. Intentially put there by a programmer.  If s/he also chooses default \n
>>>>> translation on output, \r<translation of \n> is correct.
>>>>>
>>>>>       
>>>>>           
>>>> Actually, I usually get these strings from Windows UI components. A file
>>>> containing '\r\n' is read in with '\r\n' being translated to '\n'. New
>>>> user input is added containing '\r\n' line endings. The file is written
>>>> out and now contains a mix of '\r\n' and '\r\r\n'.
>>>>     
>>>>         
>>> Out of curiosity, why don't the Python wrappers for your Windows UI
>>> components do the appropriate '\r\n' -> '\n' conversions?
>>>   
>>>       
>> One of the great things about IronPython is that you don't *need* any 
>> wrappers - you access .NET objects natively (which in fact wrap the 
>> lower level win32 API) - and the .NET APIs are usually not as bad as you 
>> probably assume. ;-)
>>
>>     
> This thread might represent an argument that you *do* need wrappers ...
>
>   
>> You just have to be aware that line endings are '\r\n'. I'm not sure how 
>> or if pywin32 handles this.
>>
>>     
> Presumably that awareness should be implemented by the "unnecessary" 
> wrappers.
>   

Well, it's an OS level difference and I thought that in general Python 
*doesn't* try to protect you from OS differences.

These different line endings are returned by the components - and making 
the string type aware of where it comes from and transform itself 
accordingly seems odd. It also leaves you with all sorts of other 
problems like string comparison (do you ignore difference in line 
endings?), string length (on different sides of the .NET / IronPython 
strings would report different lengths).

It is also different from how libraries like wxPython behave - where 
they *don't* protect you from OS differences and if a textbox has '\r\n' 
line endings - that is what you get...

Michael
http://www.manning.com/foord


> regards
>   Steve
>