Josiah, I dynamically build compound types all the time based upon .NET type information. There are some details that have to be addressed, but the correspondence for basic structures is roughly 1:1. I haven't managed to automate array creation within a structure just yet. So yeah, it can be done.
Gerd, Wasn't there something about the VLENs being turned off by default because they caused a big memory leak? I've brute-forced my way around variable length issues because I didn't want to experiment. Scott -----Original Message----- From: Hdf-forum [mailto:[email protected]] On Behalf Of Gerd Heber Sent: Tuesday, July 16, 2013 3:34 PM To: 'HDF Users Discussion List' Subject: Re: [Hdf-forum] Dynamically building a compound datatype Josiah, great questions. Compound datatypes make sense for dense data and may not be the right vehicle to approach a sparse situation. (How sparse is your data?) > 1) The message structure I'm dealing with is discovered at runtime, > while the example code uses structs that are defined at compile time. > Is there a common idiom for specifying compound datatypes dynamically? Nothing prevents you from doing an H5Tcreate(H5T_COMPOUND, size) at runtime and then add the appropriate members dynamically (via H5Tinsert). You might write some kind of type information parse, e.g., based on a JSON or XML representation. Remember though that all elements in a dataset (or attribute) must be of the same type. (Unless you make things totally opaque and loose all visibility...) > 2). The documentation indicates that datatype members can't be > variable length? > Are there common workarounds (e.g. allocating the max that a member > might need)? Where did you read that? You can have VLEN (sequence) or variable-length string members, no problem there. How efficient that can be is another story. (There's no support for compression, if you have VLENs & Co in the mix.) > 3) The documentation mentions that members can be small arrays - how > small is small? Small or big arrays. As small as an array where each element is just one byte. For fixed-size arrays, have a look at the H5T_ARRAY class (up to 32 dimensions). Best, G. _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org ________________________________ This e-mail and any files transmitted with it may be proprietary and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender. Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of Exelis Inc. The recipient should check this e-mail and any attachments for the presence of viruses. Exelis Inc. accepts no liability for any damage caused by any virus transmitted by this e-mail. _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
