Shell-style programming in Kawa

[Per Bothner]

On 01/28/2014 01:12 PM, Jamison Hope wrote:
> Nice.  If I'm following the trail correctly, that was changing a
> format directive from ~A to ~Q.  Is this ~Q directive ever useful
> in user code?  It isn't documented on the Format page of the
> website.

It would be useful for quoting of embedded expressions in DSLs.
For example:
   &sql{select * from table where name = "&[name]"}
By using ~Q the "Kawa-SQL" class can add easily add the
appropriate escape characters.

I started a blog article on this, but you can see it's
not much: http://per.bothner.com/blog/2013/Kawa-smart-substitution/

> It looks like it acts as if the format specifier were
> "\xF202~A\xF203", where #\xf202 and #\xf203 are unassigned
> characters from one of the Unicode Private Use Areas.  And then
> the consumer of the resultant string is responsible for recognizing
> these embedded unprintable marks and doing something useful (such
> as stripping out a trailing newline).  Is that right?

Basically.  When shell: is #t, then the handleMarks method may add
escape characters, so when the shell later does word-splitting it
does so more-or-less the same as when the tokenize method does if
for when shell: is false.  (FWIW, the handleMarks and tojebize
methods should pobably be merged.)

Another complication is the the characters 0xf200 and 0xf201 are used to
mark sequences.
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/