| Re: Procedures with variable/dynamic argument list?? [message #73027] |
Mon, 25 October 2010 06:51 |
Michael Galloy
Messages: 1114
Registered: April 2006
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Senior Member |
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On 10/25/10 1:32 am, SonicKenking wrote:
> Thanks all for the reply.
> It is good to be clear that it is not directly possible to make a
> dynamic argument list. I'll just go with the dummy parameter way and
> use scope_varfetch to loop on the actual passed arguments.
You can do it from within a DLM routine, though.
Mike
--
www.michaelgalloy.com
Research Mathematician
Tech-X Corporation
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| Re: Procedures with variable/dynamic argument list?? [message #73075 is a reply to message #73037] |
Fri, 22 October 2010 08:50  |
pgrigis
Messages: 436
Registered: September 2007
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Senior Member |
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On Oct 22, 11:14 am, Chris Torrence <gorth...@gmail.com> wrote:
> On Oct 22, 8:26 am, Paolo <pgri...@gmail.com> wrote:
>
>
>
>
>
>> It comes out pretty ugly indeed... here my "pritn" function
>> that I use to work around my bad spelling (!)
>> I guess I didn't know about n_params() when I wrote that.
>
>> Ciao,
>> Paolo
>
>> PRO pritn,a1,a2,a3,_extra=_extra
>
>> IF exist(a3) THEN print,a1,a2,a3,_extra=_extra ELSE $
>> IF exist(a2) THEN print,a1,a2,_extra=_extra ELSE $
>> IF exist(a1) THEN print,a1,_extra=_extra
>
>> END
>
>> ;from solarsoft
>> function exist,var
>
>> return,n_elements(var) ne 0
>
>> end
>
> Hi all,
>
> You might look at SCOPE_VARFETCH. You could dynamically construct the
> argument name, and then pass the string to SCOPE_VARFETCH to retrieve
> the value. Something like:
>
> PRO pritn,a1,a2,a3,_extra=_extra
> for i=1,n_params() do print, SCOPE_VARFETCH('a'+strtrim(i,
> 2)),_extra=_extra
> end
>
> This only helps in cases where you can break up the arguments and do a
> call with each one separately.
>
> Paolo, if I could suggest a tweak, you could use a CASE statement
> instead:
>
> case n_params() of
> 1: print,a1,_extra=_extra
> 2: print,a1,a2,_extra=_extra
> 3: print,a1,a2,a3,_extra=_extra
> else: message,'Incorrect number of arguments'
> endcase
>
Yes, the CASE version is nicer and that's how I would have
wrote it if I had known about n_params() back then... :)
You always learn something new :)
Thanks,
Paolo
> This avoids all of those nasty if/else blocks.
>
> -Chris
> ITTVIS
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| Re: Procedures with variable/dynamic argument list?? [message #73077 is a reply to message #73075] |
Fri, 22 October 2010 08:14 |
chris_torrence@NOSPAM
Messages: 528
Registered: March 2007
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Senior Member |
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On Oct 22, 8:26 am, Paolo <pgri...@gmail.com> wrote:
>
> It comes out pretty ugly indeed... here my "pritn" function
> that I use to work around my bad spelling (!)
> I guess I didn't know about n_params() when I wrote that.
>
> Ciao,
> Paolo
>
> PRO pritn,a1,a2,a3,_extra=_extra
>
> IF exist(a3) THEN print,a1,a2,a3,_extra=_extra ELSE $
> IF exist(a2) THEN print,a1,a2,_extra=_extra ELSE $
> IF exist(a1) THEN print,a1,_extra=_extra
>
> END
>
> ;from solarsoft
> function exist,var
>
> return,n_elements(var) ne 0
>
> end
Hi all,
You might look at SCOPE_VARFETCH. You could dynamically construct the
argument name, and then pass the string to SCOPE_VARFETCH to retrieve
the value. Something like:
PRO pritn,a1,a2,a3,_extra=_extra
for i=1,n_params() do print, SCOPE_VARFETCH('a'+strtrim(i,
2)),_extra=_extra
end
This only helps in cases where you can break up the arguments and do a
call with each one separately.
Paolo, if I could suggest a tweak, you could use a CASE statement
instead:
case n_params() of
1: print,a1,_extra=_extra
2: print,a1,a2,_extra=_extra
3: print,a1,a2,a3,_extra=_extra
else: message,'Incorrect number of arguments'
endcase
This avoids all of those nasty if/else blocks.
-Chris
ITTVIS
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| Re: Procedures with variable/dynamic argument list?? [message #73084 is a reply to message #73077] |
Fri, 22 October 2010 07:26 |
pgrigis
Messages: 436
Registered: September 2007
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Senior Member |
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On Oct 22, 9:56 am, "Kenneth P. Bowman" <k-bow...@null.edu> wrote:
> In article
> < d5d024b5-fb3e-438e-9277-c4dc032c3...@n24g2000prj.googlegroup s.com >,
>
> SonicKenking <ywa...@gmail.com> wrote:
>> Is it possible in IDL to code a procedure using variable/dynamic
>> argument list?? i.e. the number of arguments is arbitrary and the
>> procedure is able to accept them all with some argument array?
>
>> Similar to the "va_list" in C or "*args" in Python.
>
>> The Print command in IDL is a good example too for accepting arbitrary
>> number of arguments and print them all. Unfortunately, the Print
>> command is not written in IDL, hence no sneak peek of the source code
>> ~~
>
> IDL procedures and functions are flexible about how many
> arguments you provide, as long as you don't pass too many.
>
> You do have to provide at least as many dummy arguments
> in the procedure definition as you intend to use. That is
>
> PRO VAR_ARGS, a1, a2, a3, a4
>
> can be called as
>
> VAR_ARGS, x, y
>
> It is up to the procedure to know what to do in that
> case. (See the N_PARAMS function.)
>
> As far as I know, there is no direct mechanism for
> handling an arbitrary number of arguments other than
> making a list in the procedure/function definition.
>
> Ken
It comes out pretty ugly indeed... here my "pritn" function
that I use to work around my bad spelling (!)
I guess I didn't know about n_params() when I wrote that.
Ciao,
Paolo
PRO pritn,a1,a2,a3,_extra=_extra
IF exist(a3) THEN print,a1,a2,a3,_extra=_extra ELSE $
IF exist(a2) THEN print,a1,a2,_extra=_extra ELSE $
IF exist(a1) THEN print,a1,_extra=_extra
END
;from solarsoft
function exist,var
return,n_elements(var) ne 0
end
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| Re: Procedures with variable/dynamic argument list?? [message #73089 is a reply to message #73084] |
Fri, 22 October 2010 06:56 |
Kenneth P. Bowman
Messages: 585
Registered: May 2000
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Senior Member |
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In article
<d5d024b5-fb3e-438e-9277-c4dc032c35e2@n24g2000prj.googlegroups.com>,
SonicKenking <ywangd@gmail.com> wrote:
> Is it possible in IDL to code a procedure using variable/dynamic
> argument list?? i.e. the number of arguments is arbitrary and the
> procedure is able to accept them all with some argument array?
>
> Similar to the "va_list" in C or "*args" in Python.
>
> The Print command in IDL is a good example too for accepting arbitrary
> number of arguments and print them all. Unfortunately, the Print
> command is not written in IDL, hence no sneak peek of the source code
> ~~
IDL procedures and functions are flexible about how many
arguments you provide, as long as you don't pass too many.
You do have to provide at least as many dummy arguments
in the procedure definition as you intend to use. That is
PRO VAR_ARGS, a1, a2, a3, a4
can be called as
VAR_ARGS, x, y
It is up to the procedure to know what to do in that
case. (See the N_PARAMS function.)
As far as I know, there is no direct mechanism for
handling an arbitrary number of arguments other than
making a list in the procedure/function definition.
Ken
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| Re: Procedures with variable/dynamic argument list?? [message #73102 is a reply to message #73089] |
Fri, 22 October 2010 02:04 |
SonicKenking
Messages: 51
Registered: October 2010
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Member |
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On Oct 22, 7:57 pm, Gray <grayliketheco...@gmail.com> wrote:
> On Oct 21, 9:49 pm, SonicKenking <ywa...@gmail.com> wrote:
>
>> Is it possible in IDL to code a procedure using variable/dynamic
>> argument list?? i.e. the number of arguments is arbitrary and the
>> procedure is able to accept them all with some argument array?
>
>> Similar to the "va_list" in C or "*args" in Python.
>
>> The Print command in IDL is a good example too for accepting arbitrary
>> number of arguments and print them all. Unfortunately, the Print
>> command is not written in IDL, hence no sneak peek of the source code
>> ~~
>
> You want the _EXTRA keyword.
hmm, correct me if I am wrong. But _EXTRA is only good for accepting
extra keyword arguments, not positional arguments. I need something
similar to _Extra, but accept positional arguments.
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| Re: Procedures with variable/dynamic argument list?? [message #73103 is a reply to message #73102] |
Fri, 22 October 2010 01:57 |
Gray
Messages: 253
Registered: February 2010
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Senior Member |
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On Oct 21, 9:49 pm, SonicKenking <ywa...@gmail.com> wrote:
> Is it possible in IDL to code a procedure using variable/dynamic
> argument list?? i.e. the number of arguments is arbitrary and the
> procedure is able to accept them all with some argument array?
>
> Similar to the "va_list" in C or "*args" in Python.
>
> The Print command in IDL is a good example too for accepting arbitrary
> number of arguments and print them all. Unfortunately, the Print
> command is not written in IDL, hence no sneak peek of the source code
> ~~
You want the _EXTRA keyword.
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