st: New package -specialexp- on SSC

[Matthew White <mwhite@poverty-action.org>]

Thanks as always to Kit Baum, a new Mata function -specialexp()- is
now available for download from SSC. To install, type -ssc install
specialexp- in Stata.

-specialexp()- obtains an expression that evaluates to a specified
string. It can facilitate writing do-files that contain difficult
string literals.

To be used in an expression, most strings need only be enclosed in
double quotes. However, strings that contain the Stata special
characters `, $, or " or an ASCII control character, such as the
line-feed character (\n), may also need the \ escape character. They
may even require an expression that contains multiple strings.

Here are a few examples:

: specialexp("abc")
  "abc"

: s = "`" + "x" + "'"
: s
  `x'

: specialexp(s)
  "\`x'"

: s = "`\" + `"\${x}""y"""' + "`"
: s
  `\${x}""y""`

: specialexp(s)
  "\`\" + `"\${x}""y"""' + "`"

Best,
Matt

-- 
Matthew White
Senior Project Associate
Innovations for Poverty Action
101 Whitney Avenue, New Haven, CT 06510 USA
www.poverty-action.org
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