Some thoughts on duck typing
ambassador at fourthworld.com
Wed Jan 12 09:37:02 EST 2011
David Bovill wrote:
> If it quacks like a duck it is a duck.
> So I have some data in a variable that I want to display. I can use is an
> array/number/date - but for other types of data I'm wandering... xml should
> be easy, but harder would be to distinguish long text files from binary. Any
> ideas for hacks to distinguish:
> 1. images
> 2. sounds
> 3. video
> 4. binary blob
> 5. text
> 6. rtftext
> 7. utf8
> I think a lot of these can be tested by trying them out in various
> containers - ie can I create an image? What happens if I set the unicodetext
> of a field... but some of the work needs to be done by looking at the data
> first. So what would a duck_Type handler look like for LiveCode:
> function duck_Type someData
> case someData is an array
> return "array"
> case someData is a date
> return "date"
> case someData is a number
> return "number"
> case ???
> return "???"
> end switch
> end duck_Type
> Note - the idea is to work on data in a variable, not a file. I have a few
> handlers for looking at files - any suggestions / snippets of code?
If such metadata are needed for the variables, what would be the
downside of using an array? That way you could store/access the type
put tData into gMyDucksA["label"]["data"]
put "rtfText" into gMyDucksA["label"]["type"]
I realize that this is an obvious solution you've probably already
considered, but given the difficulties of imposing types and OOP
constructs in a typeless non-OOP language, for practical purposes such a
Lua-metatable-esque option may provide a reasonable balance between
performance and flexibility.
If an array is unsuitable for your needs I would be interested in
learning more about the problem being solved to see if there's an
LiveCode training and consulting: http://www.fourthworld.com
Webzine for LiveCode developers: http://www.LiveCodeJournal.com
LiveCode Journal blog: http://LiveCodejournal.com/blog.irv
More information about the Use-livecode