Re: st: -confirm variable- does not accept varlist (wildcards)

[Maarten Buis <maartenlbuis@gmail.com>]

On Thu, Sep 5, 2013 at 5:29 PM, Joe Canner wrote:
> I'm intrigued by your last sentence in #2.  Are you've saying you've never had occasion to use wildcards in varlists, or that there are alternatives?  For example, suppose you wanted to do something with all system-generated variables _*, knowing that these might be scattered around the dataset and not contiguous.  How would you do that without wildcards?

Nick, already stated that he did not use wildcards in combination with
-confirm-. Let me speculate why that is the case. When programming you
typically allow varlist including wildcards to be specified by the
user, but that input is parsed at the very beginning by the -syntax-
command. One of the things that the -syntax- command does is that it
unabreviates varlist and passes that on to a local macro that the
programmer uses in the rest of the program. So, after the -syntax-
command there are no longer any wildcards in the user input. It may
happen that the program creates (temporary) variables. There again I
would never use wildcards to refer to those variables, because it may
happen that there are already variables in the dataset that conform to
that pattern with wildcards, and thus break your program. Typically,
you create the variables and store their names in a local macro and
refer to that local macro further on in the program. So when
programming in Stata wildcards almost never appear after the -syntax-
command, which is usually one of the very first commands inside a
program.

> You said " I am not sure how confirm *should* work with wildcards".  According to the -confirm- documentation, not only should -confirm var- work with a varlist, but they even give an example of using it with multiple variables.

An example with multiple variables does not indicate whether or not
wildcards should be allowed. What is relevant is the statement in the
helpfile that it refers to a varlist, and it provides a link to the
help-file that defines what a varlist means in Stata: -help varlist-.
This definition includes wildcards. So it sounds to me that the
helpfile is somewhat unclear about this point and the error message
could be improved.

-- Maarten


---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
---------------------------------

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