st: Re: st: Re: st: syntax : keep variables listed in ìf'

[Steve Samuels <sjsamuels@gmail.com>]

Maarten, I think you need to add a space after each operator, or something like

"foo if mpg>rep78:

will fail.

Steve

-- 
Steven Samuels
sjsamuels@gmail.com
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On Tue, Jul 13, 2010 at 4:14 AM, Maarten buis <maartenbuis@yahoo.co.uk> wrote:
> --- On Tue, 13/7/10, SCHOUMAKER Bruno wrote:
>> I am using the syntax to prepare a stata command (ado
>> file). I used the [if] in the syntax.
>>
>> I would like find an easy way to extract the names of the
>> variables appearing in the macro ìf'.
>
> I don't know if this qualifies as easy, but it seems to work:
>
> *----------------- begin example -------------------
> program drop _all
> program define foo
>        syntax [if]
>        // add spaces between variables and operators
>        local if : subinstr local if "!"  " !" , all
>        local if : subinstr local if "==" " ==", all
>        local if : subinstr local if "<"  " <" , all
>        local if : subinstr local if ">"  " >" , all
>        local if : subinstr local if "|"  " |" , all
>        local if : subinstr local if "&"  " & ", all
>        local if : list retokenize if
>        tokenize `if'
>
>        local k : word count `if'
>        forvalues i = 1/`k' {
>                capture confirm variable ``i''
>                if !_rc {
>                        local ifvars "`ifvars' ``i''"
>                }
>        }
>        di "`ifvars'"
> end
>
> sysuse auto
> foo if mpg > 10 & displacement!= 5
> *------------------- end example -----------------------
>
> If you were to use this code I would put it in a sub-program
> to keep your code easily readable. Something like:
>
> program define main_programe
>    syntax ... [if] ...
>    ...
>    Findifvars if `if'
>    ...
> end
>
> program define findifvars, sclass
>   <code from above>
> end
>
> Hope this helps,
> Maarten
>
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
>
> http://www.maartenbuis.nl
> --------------------------
>
>
>
>
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