I see. Well, there will be an almost equally simple way of doing that,
or an equivalent, and one which certainly won't entail escaping macro
substitution.
For example, suppose you are in a loop
Within some loop {
...
tempvar foo
local xlist `xlist' i.land|`foo'
...
}
Otherwise put, I don't think there is ever a problem for which lines
like
local ldep`u' "ldep`u'"
are part of the solution.
(We had a similar thread a while back in which someone asserted that it
was sometimes necessary to delay substitution, and I kept disputing
that. It's a myth that seems to grow out of trying to translate other
programming styles to Stata macro programming.)
Nick
[email protected]
Eva Poen
Thanks, Nick.
However, your suggestion does not produce the desired result:
. di "`xlist'"
i.land|ldep0 i.land|ldep1 i.land|ldep2
While Christoph was after:
. di "`xlist'"
i.land|`ldep0' i.land|`ldep1' i.land|`ldep2'
Unless I am missing something here.
Eva
2008/7/16 Nick Cox <[email protected]>:
> I agree. In fact, I'd go one step further:
>
> foreach u of numlist 0/2{
> local xlist `xlist' i.land|ldep`u'
> }
>
> Sometimes the quotes just make things more complicated.
Eva Poen
> take it in steps and it works:
>
> foreach u of numlist 0/2{
> local xlist "`xlist' " "i.land|" "`" "ldep`u'" "'"
> }
>
>
> -di "`xlist'"- returns
>
> i.land|`ldep0' i.land|`ldep1' i.land|`ldep2'
>
> on my machine.
>
> 2008/7/16 Christoph Birkel <[email protected]>:
>
>> I want to program a loop which produces a macro `xlist' containing a
> list of
>> dummy variable interaction expansion expressions with temporary
> variable
>> names `ldep0' , `ldep1' etc. as a string . For this purpose I wrote:
>> foreach u of numlist 0/`y2'{
>> local ldep`u' "ldep`u'"
>> local xlist "`xlist' i.land|``ldep`u'''"
>> }
>> The resulting macro should contain an expression like "
i.land|`ldep0'
>> i.land|`ldep1' i.land|`ldep2' " (when `y2' contains 2) which
> can be
>> used as argument in -xi: reg-, as in: xi: reg yvar i.land `xlist' .
> (The
>> temporary variables `ldep0' and so on, corresponding to the macros
are
>> generated later in a separate loop.)
>> What actually happens, is that, due to the single quotation marks,
the
>> macros containing the names of the temporary variables are subsituted
> by
>> their content (which should not happen), so the content of the
> resulting
>> macro is " i.land|ldep0 i.land|ldep1 i.land|ldep2 ", which cannot
be
> used
>> to refer to temporary variables. For the same reason, it is not
> possible to
>> define a local macro with a string as content which starts and ends
> with
>> quotation marks. I found no way to avoid the unintended macro
> substitution
>> using "\" or compound quotes. Any recommendation is highly
> appreciated.
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