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RE: st: Problem with macro: -twoway scatter- type mismatch


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Problem with macro: -twoway scatter- type mismatch
Date   Tue, 21 Nov 2006 11:55:51 -0000

This is indeed still legal Stata. When a macro 
acquires contents by copying, then the syntax is 

local <macname> <contents> 

so that whatever follows the macro name becomes 
the contents. 

The quotes " ", on occasion `" "', have two purposes: 
to indicate to Stata where a string begins and ends; 
and to emphasise to the reader of your code -- even 
if only yourself, that usually includes yourself at a 
later date -- that a certain string is being inserted 
into the macro. Thus, for example, 

local str "a b c" 

is arguably a smidgen easier for even very experienced
Stata programmers to absorb mentally than 

local str a b c 

Sometimes that second purpose is as or more important
than the first purpose, because the meaning to Stata
is, at least in terms of result, the same in both cases. 

Quotes can be essential in some problems, as when you 
want leading or trailing spaces, as in 

local str "a b c " 

or

local str " a b c" 

-- and they rarely complicate things, but in many instances
they are at choice. 

Nick 
n.j.cox@durham.ac.uk 

Friedrich Huebler
 
> Thank you, Ben and Seb. I went through my code, removed several quote
> marks and can now make a graph with -twoway `scatter'-. I had assumed
> that string macros must be enclosed in quotes, like this:
> 
> . local str "a b c"
> 
> In the code that runs without error message, I create the string
> macros without quote marks.
> 
> . local str a b c
> 
> Is this still official Stata? All examples in [P] macro use quotes
> around the strings.

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