st: How to consecutively add elements to a macro

[Thomas Speidel <thomas@tmbx.com>]

On Wed, 02 Mar 2011 14:39:36 -0700, Thomas Speidel <thomas@tmbx.com> 
wrote:
> I am working with multiple datasets where I have to modify and
> extract variables to be assembled into a new dataset.  To keep track
> of things in my do file, I would like to create a macro, say 
> readyvar,
> which stores the variable names as they become ready:
>
> ***********EXAMPLE**************
> local readyvar
> use data1.dta
> <do something>
> save temp1
> local readyvar birthday
>
> use data2.dta
> <do something>
> save temp2
> local readyvar <want to _add_ gender to the macro>
>
> use data3.dta
> <do something>
> save temp3
> local readyvar <want to _add_ smoking to the macro>
>
> <...>
> use temp1
> merge id using temp2 temp3, sort
> keep readyvar
> **********END EXAMPLE************
>
> My question is how to I add elements to an existing macro without
> having to re-type the whole content of the macro each time?  Also, if
> I understand correctly, local macros exist only if I run the whole do
> file at once.  In other words, if I run 'chunks' of the do files one
> at a time, I would not be able to use the macro that was created in
> the previous 'chunk'.  Is this one of those cases where a global 
> macro
> is preferrable?
>
> Thank you.

--
Thomas Speidel
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