Re: structs/records in mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg41784] Re: [mg41767] structs/records in mathematica
- From: Sseziwa Mukasa <mukasa at jeol.com>
- Date: Thu, 5 Jun 2003 07:31:28 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
On Wednesday, June 4, 2003, at 08:34 AM, Sidney Cadot wrote:
> Hi All,
>
> Currently I am involved in a project to read satellite data files into
> languages such as IDL and others. We're also considering implementing
> a Mathematica interface.
>
> For this application, we need the ability to represent classical
> records/structs (as found in imperative languages such as C/Pascal),
> having named fields with an associated value.
>
> Since such a type is not directly supported in Mathematica, we'd like
> to know if there is a 'standard' way of handling this type of
> situation.
>
> We're currently thinking of using a list of rules, e.g.
>
> data = {
> id->"this_or_that",
> value->17.3,
> compound->{id->"compound_id", value->18.4}
> }
>
> but this makes selecting a value a bit awkward:
>
> value/.(compound/.data)
>
> since this is syntactically the reverse of what one would expect in a
> language like C/Pascal (data.compound.value), and the /. operator is
> left-associative (therefore requiring parentheses in case of nested
> structs).
>
> Is there perhaps a better way/standard idiom for handling situations
> like this?
>
> Best regards,
> Sidney Cadot
> Science and Technology Corp., The Netherlands
I don't know about better or a standard but you can use the downvalues
of a head to simulate a struct eg.
data[id]="this_or_that";
data[value]="17.3;
data[compound[id]]="compound_id";
data[compound[value]]=18.4;
data[compound[value]]
Regards,
Ssezi