Re: AW: st: How to use the marco names?

[Nick Cox <n.j.cox@stata.com>]

In addition to other advice, note that a major issue here is not macros, 
but the use of -display-.

-display- is quite happy to display several things one after another. It 
 is also happy to display literal strings or the contents of the names 
supplied. The " " or `" "' are essential to disambiguate.

Thus for example

di "a b c"

is an instruction to display the literal string "a b c". -display- 
neither knows nor cares what that string means.

In contrast,

di a b c

is an instruction to display the contents of a, followed by the contents 
of b, followed by the contents of c. -display- now needs to work at 
finding out what a, b and c are.

Nick

Rose a.k.a. gjhxmu@sina.com wrote:

> Dear Martin,Dan and others,
>
> I am completely confused by the use of local marco.
>
> Take some examples,
> r(files) after -fs- 
>
> r(names) after -est dir-
>
> r(mean) after -su-
>
> //maybe the three above are not local marco, but I need to use it in my following procedure.
>
> r(levels) after -levelsof-
> // it seems different when the type of variable following -levelsof- is different.
> ........
>
> How to display and use them in my follwing procedure?
> di `r(levels)'
> di `"`r(levels)'"'
> di `r(files)'
> di `"`r(files)'"'
> di `r(names)'
> di r(mean)
>
> Something similar is,
> local x="1 2"
> local x "1 2"
> local x 1 2
> local x: r(mean)
>
> Concretely, when to add single quote and double quote? when to use colon?
> especially,the difference among them.

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