[Year 12 SofDev] Records VS Classes

Fri Feb 26 13:21:16 AEDT 2016

>From my dusty memory of Visual Basic, structures and records are related.
(I refer to VB STRUCTures, rather than generic SD structures including
arrays etc as mentioned in the study design.)

VB Structures store related fields of data as a single unit in RAM during
execution, and records store related fields as a single unit  on disk.
Typically, one would read records from a random file on disk and store them
in a corresponding custom structure in RAM, which is defined as a class,
e.g.

STRUCT person
  .GivenName as string * 15
  .FamilyName as string * 25
  .dob as date
  .NumPets as integer
END STRUCT

I have vague memories of then instantiating a instance of the class
'person' (e.g. employee, customer) to actually store some data. Fields in
the structure could then be addressed with a syntax like customer.GivenName
= "Fred".

While the study design does not refer to this type of RAM-based structure
(it only names 1D arrays and records) in real life I always used records
and STRUCTures together as a team. I've always considered a structure to be
conceptually like a class.

I'd be interested in hearing more on this issue. I've always avoided
classes, inheritance, polymorphism, encapsulation and the like, and lived
quite happily without them because SD has never required their use in
theory or practice.  Even now, the requirements of a programming language
for SD (summarised here
<http://vceit.com/wp/software-development/software-development-programming-requirements-for-2016/>)
don't require the use of classes.

It is odd, however, that while classes are not mentioned anywhere in SD U3
or U4, they are referred to in Unit 2!
The intro to U2AOS1 (p.23) includes the use of "predefined classes"... but
then they do not appear anywhere in the U2O1 KK. (What happens when
something is required in the AOS discussion, but not in any of the KK or
key skills?)

But, then again, using "predefined classes" could mean nothing more than
using GUI objects like textboxes, so it's hardly a conceptual oasis for
students. They could use textboxes all day without ever needing to know
anything about classes.

I'd be happy to be corrected about anything I've got wrong in my ramblings.

Mark

On 26 February 2016 at 07:52, Baas, Benjamin B <
baas.benjamin.b at edumail.vic.gov.au> wrote:

> The study design mentions records under the dot point referring to data
> structures. To me that sounds like they want to us to look at records with
> in the programming language. In the case of the C languages and VB struts
> or structures. That’s my interpretation. I might ask Paula.
>
>
>
> ·         types of data structures, including one-dimensional arrays
> (single data type, integer index) and records (varying data types, field
> index)
>
>
>
> Cheers,
>
>
>
> Ben.
>
>
>
> *From:* sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au] *On Behalf Of *Paragreen, Chris J
> *Sent:* Thursday, 25 February 2016 3:40 PM
> *To:* Year 12 Software Development Teachers' Mailing List <
> sofdev at edulists.com.au>
> *Subject:* Re: [Year 12 SofDev] Records VS Classes
>
>
>
> My interpretation is that we need to teach records as in files and
> records, as opposed to the language specific data structure. How you then
> implement the record is up to … you? … the students? I’m also thinking that
> might tie into XML and the importing and exporting of data. Please tell me
> if my interpretation is wrong!
>
>
>
> Chris
>
>
>
> *From:* sofdev-bounces at edulists.com.au [
> mailto:sofdev-bounces at edulists.com.au <sofdev-bounces at edulists.com.au>] *On
> Behalf Of *Laurie Savage
> *Sent:* Thursday, 25 February 2016 2:03 PM
> *To:* Year 12 Software Development Teachers' Mailing List <
> sofdev at edulists.com.au>
> *Subject:* Re: [Year 12 SofDev] Records VS Classes
>
>
>
> Always a good idea to teach what is in the study design even if current
> practice is moving past it.
>
>
>
> Laurie Savage
>
> PVGC
>
>
> Laurie Savage
> https://sites.google.com/a/pvgc.vic.edu.au/mr-savage/home
>
>
>
> On 25 February 2016 at 13:15, Baas, Benjamin B <
> baas.benjamin.b at edumail.vic.gov.au> wrote:
>
> Hi all,
>
>
>
> I just wanted to get people’s opinions, as part of the study design we
> have to teach our students  about record data structures. If we have to use
> an OO language would it not be best to just teach them how to make classes.
>
>
>
> I haven’t done structs in C# before, only C, and to me it feels like I
> should just teach me students how to make basic classes and not worry about
> teaching sturcts. I will teach them structs as that’s what the study design
> says.
>
>
>
> Cheers,
>
>
>
> Ben.
>
>
>
> *Benjamin Baas*
>
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-- 

Mark Kelly

mark at vceit.com
http://vceit.com
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