st: dynamic line execution in mata

[Andrew Maurer <Andrew.Maurer@qrm.com>]

Hi Statalist,

I am trying to find Mata's equivalent of Stata's macro expansion functionality. In the below example, I first define an object thisvar as the string "date" and I define the object date as the column vector 1 \ 2 \ 3 \ 4 \ 5. How can I return the contents of the "date" object by only referencing "thisvar"? 

In the line, rows( thisvar ), thisvar is simply the 1x1 matrix containing the string "date", so rows( thisvar ) returns: 1. What I am looking for is something like rows( `=thisvar' ), so as to return 5 rather than 1.

********* begin example *********

mata

i = 1
date = 1 \ 2 \ 3 \ 4 \ 5
varnames = "date", "price"
thisvar = varnames[1,i]
rows( thisvar ) // output: 1
rows( date ) // output: 5

end

********* end example ***********

Thank you,
Andrew Maurer


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