Indirect assignment of empty matrix

[IanWakeling]

I was surprised recently to get a "Matrix has not been set to a value" error when attempting to assign an empty matrix using VALSET.  If the syntax

x = {};

is acceptable, should it not be possible to do the same thing indirectly?  For example,

call valset('x', {});

will generate the error referred to above.  My actual code is more complex, where the 2nd argument to VALSET is a function that might occasionally return an empty matrix, so I have simplified things above to illustrate the point.  I am using SAS/IML 15.1.

[Rick_SAS]

You are correct. I do not have a workaround when the name of the symbol is not known until run time, since the FREE statement requires a symbol name, not a character string.

My only suggestion is to ask whether the function can return a missing value instead of an empty matrix. In my work, I often use a missing value to indicate an operation failed. It is easier to work with than an empty matrix.

[IanWakeling]

Thanks for your reply Rick.  I am still experimenting with Lists in IML, and I am using ListGetAllNames() which returns an empty matrix if there are no names associated with the list items.   I am sure I will find a workaround.

[Ksharp]

IsEmpty(x)  could detect if x is empty .