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Re: Fwd: st: -args- how to flag when missing or too many arguments


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: Fwd: st: -args- how to flag when missing or too many arguments
Date   Fri, 22 Mar 2013 10:21:51 +0000

Here is another way to approach it, building on earlier suggestions.

numlist "`1' `2' `3' `4' `5'", int min(4) max(4)
args a b c d

If 3 or fewer arguments are specified, the test will fail.

If 5 or more arguments were specified, "`5'" will be non-empty and the
test will fail. But you must mention `5' for it to test.

Or you could just use `0'.

numlist "`0'", int min(4) max(4)

With this, we need not name the arguments until we know we have the
right number.

If the logic is right, then the differences are mostly of taste,
except that simplicity and clarity should appeal universally.

Details differ if there are other elements to the syntax, such as options.

A program that takes on only numerical arguments might qualify as an
"immediate" command. Start with -help immediate- for suggestions. It's
a good convention that immediate command names end with "i", although
the converse need not be true.

Nick

On Fri, Mar 22, 2013 at 8:47 AM, John Antonakis <John.Antonakis@unil.ch> wrote:
> OK. Thanks Nick.....and I meant to say "doesn't do anything".
>
>
> Best,
> J.
>
> __________________________________________
>
> John Antonakis
> Professor of Organizational Behavior
> Director, Ph.D. Program in Management
>
> Faculty of Business and Economics
> University of Lausanne
> Internef #618
> CH-1015 Lausanne-Dorigny
> Switzerland
> Tel ++41 (0)21 692-3438
> Fax ++41 (0)21 692-3305
> http://www.hec.unil.ch/people/jantonakis
>
> Associate Editor
> The Leadership Quarterly
> __________________________________________
>
> On 22.03.2013 09:38, Nick Cox wrote:
>>
>> ---------- Forwarded message ----------
>> From: Nick Cox <njcoxstata@gmail.com>
>> Date: Fri, Mar 22, 2013 at 8:30 AM
>> Subject: Re: st: -args- how to flag when missing or too many arguments
>> To: statalist@hsphsun2.harvard.edu
>>
>>
>> John: You should know that the Statalist FAQ advises against "does not
>> work" as an error report.
>>
>> if "`chi'" == ""
>>
>> is sufficient as a test of there not being four arguments. Whether
>> there are none, one, two, or three, it follows in each case that there
>> was no fourth argument.
>>
>> Your code does not test that the arguments are integers (which you can
>> do in one line with -numlist-).
>>
>> Nick
>>
>> On Fri, Mar 22, 2013 at 7:51 AM, John Antonakis <John.Antonakis@unil.ch>
>> wrote:
>>>
>>> Thanks Nick.  That works.
>>>
>>> With respect to flagging less than four Austin gave me some nice code
>>> that
>>> works. Following Nick's approach, the below doesn't work and I can't see
>>> why:
>>>
>>>    ...
>>>    args no_vars df N chi too_much
>>>
>>> *nick's part, works
>>>    if "`too_much'" != "" {
>>>    di as err "Too many arguments. "
>>>    exit 198
>>>    }
>>>
>>> *my part, does not work
>>>    if "`no_vars'"=="" | "`df'"=="" | "`N'"=="" | "`chi'"=="" {
>>>    di as err "You have to use four integers. "
>>>    exit 498
>>>
>>>    }
>>>
>>> Best,
>>> J.
>>>
>>> __________________________________________
>>>
>>> John Antonakis
>>> Professor of Organizational Behavior
>>> Director, Ph.D. Program in Management
>>>
>>> Faculty of Business and Economics
>>> University of Lausanne
>>> Internef #618
>>> CH-1015 Lausanne-Dorigny
>>> Switzerland
>>> Tel ++41 (0)21 692-3438
>>> Fax ++41 (0)21 692-3305
>>> http://www.hec.unil.ch/people/jantonakis
>>>
>>> Associate Editor
>>> The Leadership Quarterly
>>> __________________________________________
>>>
>>> On 22.03.2013 02:46, Nick Cox wrote:
>>>>
>>>> My approach for these problems is -- in a case with only 4 arguments
>>>> wanted --
>>>>
>>>> args a b c d garbage
>>>>
>>>> if "`garbage'" != ""
>>>>          di as err "too many arguments"
>>>>          exit 198
>>>> {
>>>>
>>>> On Thu, Mar 21, 2013 at 10:14 PM, John Antonakis
>>>> <John.Antonakis@unil.ch>
>>>> wrote:
>>>>>
>>>>> Thanks, Austin.
>>>>>
>>>>> This works too, except for when w > 4; it does not display the error.
>>>>> The
>>>>> program just ignores any arguments beyond 4 arguments (as is the
>>>>> default
>>>>> in
>>>>> Stata).
>>>>>
>>>>>
>>>>> Best,
>>>>> J.
>>>>>
>>>>> __________________________________________
>>>>>
>>>>> John Antonakis
>>>>> Professor of Organizational Behavior
>>>>> Director, Ph.D. Program in Management
>>>>>
>>>>> Faculty of Business and Economics
>>>>> University of Lausanne
>>>>> Internef #618
>>>>> CH-1015 Lausanne-Dorigny
>>>>> Switzerland
>>>>> Tel ++41 (0)21 692-3438
>>>>> Fax ++41 (0)21 692-3305
>>>>> http://www.hec.unil.ch/people/jantonakis
>>>>>
>>>>> Associate Editor
>>>>> The Leadership Quarterly
>>>>> __________________________________________
>>>>>
>>>>> On 21.03.2013 22:54, Austin Nichols wrote:
>>>>>>
>>>>>> John Antonakis <John.Antonakis@unil.ch>:
>>>>>> You might also want to step through various conditions and then issue
>>>>>> a more informative error message at the end, e.g. consider adapting
>>>>>> this approach:
>>>>>>
>>>>>> cap prog drop john
>>>>>> prog john, rclass
>>>>>>     version 12
>>>>>>     loc err 0
>>>>>>     args no_vars df N chi
>>>>>>     loc w: word count `no_vars' `df' `N' `chi'
>>>>>>     if `w'>4 {
>>>>>>      loc err 1
>>>>>>      di in red "More than 4 arguments given"
>>>>>>      }
>>>>>>     foreach v in no_vars df N chi {
>>>>>>      cap confirm integer number `=``v'''
>>>>>>      if _rc!=0 {
>>>>>>       loc err 1
>>>>>>       di in red "Arguments must be integers."
>>>>>>       }
>>>>>>      else if ``v''<0 {
>>>>>>       loc err 1
>>>>>>       di in red "Arguments must be positive integers."
>>>>>>       }
>>>>>>      }
>>>>>>     if `err'==1 {
>>>>>>      di in red "Please enter data after the command" _c
>>>>>>      di in red " john as follows: vars df N chi"
>>>>>>      exit 198
>>>>>>      }
>>>>>> end
>>>>>>
>>>>>> On Thu, Mar 21, 2013 at 5:49 PM, daniel klein
>>>>>> <klein.daniel.81@gmail.com>
>>>>>> wrote:
>>>>>>>
>>>>>>> John,
>>>>>>>
>>>>>>> I think I would address this with something like this
>>>>>>>
>>>>>>> cap pr drop john
>>>>>>> pr john
>>>>>>>            vers 12.1
>>>>>>>
>>>>>>>            args a b c d
>>>>>>>            if !inrange(`: word count `0'', 1, 4) {
>>>>>>>                    di as err "Please enter data after " ///
>>>>>>>                    "the command john as follows: vars df N chi"
>>>>>>>                    e 198
>>>>>>>            }
>>>>>>>            numlist "`0'" ,int r(>0)
>>>>>>>
>>>>>>> end
>>>>>>>
>>>>>>> Best
>>>>>>> Daniel
>>>>>>> --
>>>>>>> Hi:
>>>>>>>
>>>>>>> I am writing a program and would like Stata to return an error if an
>>>>>>> argument is missing or there are too many of them.
>>>>>>>
>>>>>>>
>>>>>>> For example, if an argument is not an integer, the below will return
>>>>>>> an
>>>>>>> error:
>>>>>>>
>>>>>>>
>>>>>>>      program define john, rclass
>>>>>>>      version 12
>>>>>>>      args no_vars df N chi
>>>>>>>
>>>>>>>      if `no_vars'<0 | `df'<0 | `N'<0 | `chi'<0 {
>>>>>>>      di in red "You have to use integers."
>>>>>>>      exit 498
>>>>>>>      }
>>>>>>> end
>>>>>>>
>>>>>>> Now, how do I make Stata display:
>>>>>>>
>>>>>>> di in red "Please enter data after the command john as follows: vars
>>>>>>> df
>>>>>>> N
>>>>>>> chi"
>>>>>>>
>>>>>>>
>>>>>>> .....in cases where (a) there is a missing value (i.e., the user
>>>>>>> missed putting 4 numbers) and (b) if the user provides too many
>>>>>>> numbers (i.e., 5 instead of 4).
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