| Error handling by build-in IDL routines [message #14664] |
Mon, 15 March 1999 00:00  |
Frank Holland
Messages: 3
Registered: March 1999
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Junior Member |
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Hi!
I have a question about error handling by build-in IDL routines.
Consider the following example:
fritz = 'the cat'
print, median(fritz)
IDL replies with:
% MEDIAN: Expression must be an array in this context: FRITZ.
% Execution halted at: $MAIN$
My question:
How does the function MEDIAN knows the name of the parameter (i.e.
FRITZ) I passed into it? How can I implement this functionality into my
own IDL routines?
Thanks for any suggestions,
Frank
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| Re: Error handling by build-in IDL routines [message #14718 is a reply to message #14664] |
Sat, 20 March 1999 00:00  |
William Daffer
Messages: 34
Registered: February 1999
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Member |
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"R.Bauer" <R.Bauer@fz-juelich.de> writes:
> Vapuser wrote:
>
>> "R.Bauer" <R.Bauer@fz-juelich.de> writes:
>>
>>> Try this!
>>>
>>> PRO t2,test
>>>
>>> HELP,/recall,output=output
>>> for_test=(STR_SEP(output[1],','))[1]
>>> varsize=SIZE(routine_names(for_test,fetch=-1),/type)
>>> VarValue = Routine_Names(for_test, FETCH=-1 )
>>>
>>> IF test EQ varvalue THEN IF varsize NE 4 THEN $
>>> MESSAGE,'Expression must be of type FLOAT:'+for_test,/info
>>>
>>> END
>>>
>>> dd='dummy'
>>> t2,dd
>>>
>>> % T2: Expression must be of type FLOAT:dd
>>>
>>>
>>> R.Bauer
>>
>> I don't think this work in a procedure.
>>
>> If anyone out there in RSI land is listening...
>>
>> It would be nice to have a function like the Perl package Carp.pm,
>> which reports errors from the line number of the invocation of Carp's
>> calling routine. So, say you have a perl routine foo which reports
>> some error by calling carp. The linenumber given in the error message
>> emitted by Carp is the line at which foo is called, not the line at
>> which Carp is called. That way, you can write error handling code that
>> doesn't have to keep track of the stack, and depend on the output from
>> help.
>
> help,call=call reports this.
>
> another example for working in a procedure is:
> called by t3 :
>
> IDL> t3
> % T2: Expression must be of type FLOAT:doof
>
>
> both are seperate files.
>
>
> PRO t3
>
> doof=1
> t2,doof
>
> END
>
> -----------
>
> PRO t2,test
>
> IF N_PARAMS() LT 1 THEN BEGIN
> MESSAGE,'Try: t2,test',/info
> RETURN
> ENDIF
>
> HELP,call=call
> ; T2 <C:\t2.pro( 8)>
> ; T3 <C:\t3.pro( 4)>
> ; $MAIN$
>
> help_of_interest=within_brackets(call[1],brackets=['<','('])
> IF help_of_interest EQ '' THEN BEGIN
>
> HELP,/recall,output=output
> for_test=(STR_SEP(output[1],','))[1]
>
> varsize=SIZE(routine_names(for_test,fetch=-1),/type)
> VarValue = Routine_Names(for_test, FETCH=-1 )
>
> IF test EQ varvalue THEN IF varsize NE 4 THEN $
> MESSAGE,'Expression must be of type FLOAT:'+for_test,/info
>
> ENDIF ELSE BEGIN
> txt=get_file(help_of_interest)
> line=within_brackets(call[1],brackets=['(',')'])
> ;4
> cmd=txt[line-1]
> for_test=(STR_SEP(cmd,','))[1]
> varsize=SIZE(routine_names(for_test,fetch=-1),/type)
> VarValue = Routine_Names(for_test, FETCH=-1 )
>
> IF test EQ varvalue THEN IF varsize NE 4 THEN $
> MESSAGE,'Expression must be of type FLOAT:'+for_test,/info
> ENDELSE
>
> END
>
>
>
Thanks! This looks pretty useful!
whd
--
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