Sergiy Radyakin <[email protected]> reports,
> I want to return a string among the r() values from a Mata function.
>
> According to the manual, the following function is to be used in this case:
> > st_strscalar(string scalar name, string value)
> [...]
>
> It does not seem to work however. The following is what happened:
> **-------------1--------------------------------------------------
> : mata clear
> : void function my_test() {
> > st_strscalar("r(my_name)" ,"my_value")
> > }
> : my_test()
> st_strscalar(): 3300 argument out of range
> my_test(): - function returned error
> <istmt>: - function returned error
> r(3300);
>
> As an alternative, I tried to store my string value to a local via st_local:
> **-------------2--------------------------------------------------
> : mata clear
> : void function my_test() {
> > st_local("r(my_name)" ,"my_value")
> > }
> : my_test()
> _r(my_name) invalid name
> st_local(): 3300 argument out of range
> my_test(): - function returned error
> <istmt>: - function returned error
> r(3300);
First, "string scalars" are not currently allowed in r(), and that is why
Mata gave an error when Sergiy coded
st_strscalar("r(my_name)" ,"my_value")
What he coded would be correct syntax if Stata had string scalars.
Stata expects strings in r() to be returned in macros. Sergiy tried,
st_local("r(my_name)" ,"my_value")
but that did not work. What would have worked is
st_global("r(my_name)" ,"my_value")
and here's a demonstration:
. mata
----------------------------------------- mata (type end to exit) -----
: st_rclear()
: st_global("r(myname)", "a string value")
: end
-----------------------------------------------------------------------
. ret list
macros:
r(myname) : "a string value"
. _
It's a fine point, but things like r(myname) are considered to be global
macros and not local macros because those macros are exposed outside of
the program that set them.
-- Bill
[email protected]
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