Forcing quote characters in repr(STRING), how?

[Scott David Daniels]

On 12 Apr 2002 21:48:25 -0400, pinard at iro.umontreal.ca (=?iso-8859-1?q?Fran=E7ois?= Pinard) wrote:
..
> Despite not recommended, I nevertheless followed the trick above in Pymacs.
> Preceded by a long comment, the little piece of code looks almost clean :-).
> 
>     [...]
>     elif type(value) == types.StringType:
>         # Python delimits a string it by single quotes preferably, unless
>         # single quotes appear within the string while double quotes do
>         # not, in which case it uses double quotes for string delimiters.
>         # Checking the string contents, the C code stops at the first NUL.
>         # We prefix the string with a single quote and a NUL, this forces
>         # double quotes as delimiters for the whole prefixed string.  Then,
>         # we get rid of the representation of the single quote and the NUL.
>         write('"' + repr("'\0" + value)[6:])
>     [...]

I'd just add a slight tweak tbe a nickel faster:
..
    # Python delimits a string it by single quotes preferably, unless
    # single quotes appear within the string while double quotes do
    # not, in which case it uses double quotes for string delimiters.
    # Checking the string contents, the C code stops at the first NUL.
    # We prefix the string with a single quote, a NUL,, and a double 
    # quote -- this not only forces double quotes as delimiters for the
    #  whole prefixed string, it then follows that with a backslash and 
    # double quote, forcing the initial cruft to end in a double quote.
    # The resulting string will always begin "'\0\"...  by dropping the
    " "'\0\ part of the repr, we are left with a perfeectly fine repr.
    write(repr("'\0\"" + value)[6:])
 
This saves one string creation.
Isn't fiddling code fun?

-Scott David Daniels
Scott.Daniels at Acm.Org