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Re: dlm creating an array?
Randall Skelton wrote:
> Hello all,
> Is there a way to make a dlm that creates an IDL array?
> i.e. I am writing a simple file reading dlm that reads a binary file and
> generates a 1 dimensional array (or vector) and I would like this array
> returned to IDL such that the function syntax is something like:
> IDL> return = file_reader("test.bin", a);
> where "return" is for error checking, "test.bin" is the file to read, and
> "a" is what I would like the *new* array to be called.
> Is there something like, "IDL_StoreArray" as opposed to "IDL_StoreScalar?"
> Any and all hints and suggestions are greatly appreciated!
Two ways. Here is the better:
void test_array(int argc, IDL_VPTR argv)
/* Make Sure we can write to it, free anything already associated */
IDL_VarCopy(tmp,argv); /* This is the key. Copy tmp to passed arg
That is, you make a temporary array, and copy it over to the passed
argument (no data is actually copied, since it's a temporary). The
StoreScalarZero makes sure it's passed by reference.
This method is easiest. Another way is to make your own data, and then
use IDL_Import_Array to wrap an IDL_VPTR around it (also no copying
performed). They are basically equivalent, but the typing is more up
front with a the temporary variable method.
Please note that I did not free the tmp VPTR with IDL_DelTmp(). Why?
Because it was already reclaimed by IDL_VarCopy (which in this case is
more of a renaming than a copy). Doing so twice is a no-no.
What if you have an arbitrary number of dimensions (read from the file
perhaps)? I'd simply declare dim[IDL_MAX_ARRAY_DIM] instead, and test
to ensure this limit isn't surpassed.