comp.lang.idl-pvwave archive - RDF feed
type: channel
description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: Re: Implicit None for IDL???

Re: Implicit None for IDL???
type: item
description: In article <3snheg$63a@senator-bedfellow.MIT.EDU>, davis@space.mit.edu (John E. Davis) writes: |> Hi, |> |> Is there anyway to get IDL 4.0 to signal and error if a variable is |> undefined? I realize that IDL will generate a runtime error for this kind |> of mistake: |> |> some_variable = 3 |> ; Now double its value |> some_variable = 2 * some_vriable ; Oops spelling error! |> |> However, this mistake will not be caught by idl: |> |> some_variable = 3 |> ; Now double its value |> some_vriable = 2 * some_variable |> |> If this is not possible, is there a lint for the language, e.g., something |> to generate a message like: |> |> something.pro: line 27: `some_vriable' unused. |> |> Thanks, |> --John |> |> This question deserves serious consideration as "QUESTION OF THE YEAR!" I use implicit none in all my FORTRAN development... it is the safest way to create massive amounts of error-free code, but I have never seen a way to implement this in IDL, and that is one reason I believe IDL is not well suited for development of large applications. Another problem is that variables can suddenly change type within IDL, consider this simple example... j = 1L & foo = 1. i = 2*2 & help, i ; i is a Short integer i = i*j & help, i ; i is a Long integer i = i * foo & help, i ; i is Real this feature is great for many situations, but again, in a large application this may not be what is wanted by an uncareful programmer, but it is a difficult thing to control within 10,000 lines of code. IDL is a powerful language, but it does require one to be mighty careful. The fix, long, float, complex, etc... functions must be used wisely! I hope you receive an answer (rather than a reply like this one) to your interesting question. -- Andrew F. Loughe email: afl@cdc.noaa.gov University of Colorado, CIRES voice: (303) 492-0707 Campus Box 449 fax: (303) 497-7013 Boulder, CO 80309-0449 USA
creator: afl
date: 1995-06-27T07:00:00-00:00