Comments on: Working with structs

By: Jiro Doke

Jiro Doke — Thu, 09 Mar 2006 17:08:31 +0000

Andrew,
Yes, if the original check is there, then that out be shorter. We can combine everything, and say:

if ~isstruct(D) || …
~isequal(sort(fieldnames(D)),{’amplitude’;’time’})
error(‘snippet:incorrectInput’, …
‘snippet expects a struct with only fields time and amplitude’);
end

By: Andrew Newell

Andrew Newell — Thu, 09 Mar 2006 15:27:03 +0000

Here is a shorter test:
if length(fieldnames(D)) > 2

Andrew

By: Loren

Loren — Thu, 09 Mar 2006 12:50:52 +0000

Though the syntax looks the same, the mechanism in MATLAB is quite different. I don’t have any immediate suggestions here but you might contact our technical support team to see if they have something that might help you out.

http://www.mathworks.com/support/contact_us/ts/help_request_1.html

By: Markus

Markus — Thu, 09 Mar 2006 11:38:34 +0000

Hi!

Am working intensely with classes and objects in my MATLAB projects. As you wrote about structures which are somehow similar, I thought my question could fit in here.

When referencing or changing a field of an object, I want to use a simple dot notation like x = obj.x or obj.x = x from whatever function I am in, thus I need to implement the functions subsref.m (subscripted reference) and subsasgn.m (subscripted assignment). In my work, these functions look the same for all classes:

function value = subsref(obj, S)
value = subsref(struct(obj), S);

function obj = subsasgn(obj, S, value)
obj = builtin(‘subsasgn’, obj, S, value);

Unfortunately, the object field access is very slow, orders of magnitude slower than accessing fields of a structure. The profiler shows that the amount of time spent for accessing fields in my project is everything else than neglible.

Do you have any suggestions how to speed up field access?

Regards
Markus

By: Jiro Doke

Jiro Doke — Wed, 08 Mar 2006 22:39:33 +0000

Hi,

I love extra credit!

How about:

if ~isequal(sort(fieldnames(D)),{‘amplitude’;'time’})
error(…)
end

jiro