[Proj] quoting +nadgrids ?

Glynn Clements glynn at gclements.plus.com
Mon Aug 2 14:52:22 EST 2010

Eric Miller wrote:

> >> I had proposed the @@@space@@@ idea just because it wouldn't be interpreted
> >> anywhere else, though it is somewhat peculiar.  Can you, or anyone,
> >> provide an argument for a different approach?  Were you suggesting url
> >> encoding because it was easily extended to other escaping operations?
> > 
> > Mostly because it's already known, can be used to escape arbitrary
> > characters, the % sign seems (to me) unlikely to occur in an argument,
> > and the worst case for the size of an escaped string isn't too bad
> > (three times the size of the original string).
> > 
> > [Needless to say, the first question which crossed my mind regarding
> > the @@@space@@@ idea was: what happens if the text "@@@space@@@"
> > occurs in an argument value? Replacing each @ with @@@atsign@@@ would
> > get ugly. But that's more of a theoretical issue than a practical
> > one.]
> For whatever reason, the escape character for cmd.exe is the caret
> ^. Besides the space character, the following characters must be
> escaped: <, >, |, &, and ^ (of course). Obviously, if you use this
> escaping mechanism on Windows, the result won't be portable. URL
> encoding would not escape the ampersand, which could be trouble.

This issue has nothing (directly) to do with the shell on any
platform. It's simply an issue of how to represent a list of strings
as a single string.

Also, URL encoding can encode any character. The choice of which
characters are encoded doesn't affect the decoding algorithm.

Glynn Clements <glynn at gclements.plus.com>

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