st: Detecting a macro expansion error

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

Hi all,

Using Stata 11.2 SE, I'm writing a program that requires me to parse a
string passed to the program. I want the program to exit if the string
contains a macro expansion that results in an error. Currently, Stata
displays an error about the macro expansion without exiting, and then
continues to parse the string and run the program. Generally, I want
to know how I can detect whether a command results in a macro
expansion error. Here's an example of what I mean:

. display "`='Hello world"
invalid syntax
Hello world

Here, the macro expansion `=' results in an invalid syntax error, but
-display- is still executed (after `=' evaluates to ""), and there's
no return code (r(198) is not displayed). -capture- doesn't help:

. capture display "`='Hello world"
invalid syntax

. display _rc
0

Essentially what I'd like is something like -capture- that I can use
to determine whether a command results in a macro expansion error. Any
ideas?

Thank you,
Matt

-- 
Matthew White
Data Coordinator
Innovations for Poverty Action
101 Whitney Avenue, New Haven, CT 06510 USA
+1 434-305-9861
www.poverty-action.org
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