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Re: Possible to create 'keyword_used' type function? [message #88716 is a reply to message #88715]

Mon, 09 June 2014 15:27

Chip Helms
Messages: 24
Registered: November 2012

Junior Member

With a little bit of messing around (while watching code run) I managed to cobble this together:

; This function is equivilent to "n_elements(var) ne 0 or arg_present(var)"
; key := variable to be checked
function keyword_used, key
; grab list of variables at scope of parent routine
varnames = scope_varname(key,level=-2, count=nvar)
; determine if keyword is used as per arg_present function
; also protect against varnames begin undefined
argtest = (nvar ne 0) ? total(varnames ne '') ne 0 : 0b
; return results of test for keyword presence
return, n_elements(key) ne 0 or argtest
end

I don't think it will work unless you're calling it inside of another routine since calling it at $main$ will make it try to look at the level above $main$. You could probably add a check that uses scope_level to determine if keyword_used was called from $main$ (if it was, scope_level will return a value of 2 I think, but I could be wrong). Here's an example routine that uses keyword_used:

; demonstrate function
pro test, var=invar
if keyword_used(invar) then print, 'KEYWORD_USED indicates keyword present' else $
print, 'KEYWORD_USED indicates keyword missing'
if n_elements(invar) ne 0 or arg_present(invar) then $
print, 'Two part check indicates keyword present' else print, 'two part check keyword missing'
end

From what I can tell, when you call scope_varname with the variable argument (as done here), it traces the variable back to the requested scope level. So if you use the example routine above by calling "test, var=blah" then scope_varname in keyword_used will start from "key" and see that it was named "invar" at level=-1, and "blah" at level=-2 (i.e. the level at which test was called). It's possible I'm not understanding this correctly, but it seems to be how it behaves.

Cheers,
Chip

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[Message index]

		Possible to create 'keyword_used' type function? By: Brian Devour on Mon, 09 June 2014 14:11
		Re: Possible to create 'keyword_used' type function? By: Chip Helms on Mon, 09 June 2014 15:27
		Re: Possible to create 'keyword_used' type function? By: Chip Helms on Mon, 09 June 2014 15:42
		Re: Possible to create 'keyword_used' type function? By: Fabzi on Tue, 10 June 2014 00:48
		Re: Possible to create 'keyword_used' type function? By: Michael Galloy on Tue, 10 June 2014 08:11
		Re: Possible to create 'keyword_used' type function? By: Brian Devour on Tue, 10 June 2014 13:19
		Re: Possible to create 'keyword_used' type function? By: Chip Helms on Fri, 13 June 2014 10:13

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