The features described in this topic are obsolete
and should not be used in new IDL code.

Routines with Obsolete Arguments or Keywords

This chapter contains documentation for arguments and keywords that have been removed from IDL routines. New IDL code should not use these parameters. See IDL API History (IDL Reference Guide) for a list of obsolete parameters and their replacements, if suitable replacements exist.

When IDL attempts to execute a routine called with an obsolete argument or keyword, one of the following things will happen:

  1. The routine may function as originally designed, with no change in behavior. This is often the case when the obsolete parameter has been replaced by another parameter with a more efficient or slightly different mechanism. In these cases, the obsolete parameter is generally re-implemented within the routine to use the mechanism of the new parameter, allowing code that uses the obsolete parameter to run unaltered. Note that although the results will be the same as before the parameter became obsolete, the code may run more efficiently if the replacement parameter is used instead of the obsolete parameter.

    2. Example: The GROUP keyword to the DIALOG_PICKFILE routine was replaced by the DIALOG_PARENT keyword. Code that uses the GROUP keyword continues to run as it always did.

  2. The routine may quietly accept the parameter, but ignore its presence. This is the case when the presence of the obsolete parameter does not change the result returned by the routine. For example, parameter that affected attributes only available on certain platforms may simply be ignored on other platforms. Code using obsolete parameter of this type can run unaltered.

    3. Example: The MACTYPE keyword to the OPEN routine changed an attribute of files on pre-OS X Macintosh filesystems that has no corollary on other filesystems. IDL simply ignores the presence of this keyword.

  3. The routine may generate an error. This is the case when the presence of the obsolete parameter changes the result returned by the routine. For example, parameter that affected the returned data in some way that is no longer supported must now be removed from IDL code before it will run.

    4. Example: The DTOGFLOAT keyword to the BYTEORDER routine converted data to a format only supported under VMS. The underlying mechanism used is not available in other operating systems, and IDL will generate an error if such a conversion is specified in the call to BYTEORDER.

In all cases, if IDL code containing calls to obsolete parameter compiles and runs without error, the results are the same as they would have been before the parameter was made obsolete.