Returning a reference to 'this'

Mightor

Hey there,

I am fiddling about with the SimpleDebug Object I pulled from the Object Exchange. What I'd like to do is allow for a construction like this: (.nl is a new function I made that prints a new line & carriage return).

OBJ
  Debug : "SimpleDebug"

PUB Howdy
  Debug.start(57600) 
  Debug.str(string("Hello World")).nl

However, that would require the Debug object being able to return a reference to itself, a bit like C++'s 'return this;'. Is this even possible in SPIN?

Gr,
Mightor

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| What the world needs is more geniuses with humility, there are so few of us left.
| "Wait...if that was a compliment, why is my fist of death tingling?"
| - Alice from Dilbert

deSilva

ROFL

Mightor

deSilva said...
ROFL

Oh dear. Is that a no then? [noparse]:)[/noparse]

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| What the world needs is more geniuses with humility, there are so few of us left.
| "Wait...if that was a compliment, why is my fist of death tingling?"
| - Alice from Dilbert

Mike Green

That's a no. Objects in Spin are very limited. They're essentially a namespace with a static per-instance variable space. The variables are known only within the object source file except that named constants and procedures/functions (methods) marked public (PUB) are accessible from outside as long as they have an instance prefix. Multiple instances use shared code and shared data (DAT).

Graham Stabler

Bad deSilva, bad!

[noparse]:)[/noparse]

mirror

Mightor,

If you're wanting a serial port that can be accessed from multiple spin files, then try SerialMirror:

http://forums.parallax.com/showthread.php?p=649541

The concepts can also be used to make other objects visible/useable in multiple spin files.·

Phil Pilgrim (PhiPi)

Mightor,

I'm not completely sure what you're trying to do (since I'm not a C++ programmer), but I suspect my callback facility might be of some use. Anyway, you can check it out here:

····http://forums.parallax.com/showthread.php?p=593662

It breaks some rules and needs to be used with caution, but it may prove useful, nonetheless.

-Phil

Mightor

What I am trying to do is this. In C++ and many other OO languages it is possible for an instance of an object to return a reference to itself. This allows you to chain commands using the . operator. Say you have an object instance named foo with a member function called baz. The baz function, besides doing some operations, also return a reference to the foo instance.
Calling foo.baz() would then return a reference to foo again. This would allow for something like foo.baz().baz(). This can be very handy in some cases.

Phil,
Hehe, your code intimidates me a little and if it takes voodoo magic to accomplish something like this then it's not really worth it for me. I would probably spend more time trying to figure out a bug I caused trying to copy your code appropriately than actually learning to use this SPIN language. I am still quite new to it, as I've only had my board since last Friday or so.

Mirror,
I had seen posts of yours before mentioning the SerialMirror object, I will check it out later [noparse]:)[/noparse] Is there any chance you can upload it to the CodeExchange site? That will give it a lot more exposure, too. You can find that here: http://ww1.parallax.com/SupportDownloads/PropellerLibrary/tabid/65/Default.aspx, I have no idea what is involved in getting access to it, but I am sure it is mentioned on there somewhere.

I think for now I will just stick with two lines of code [noparse]:)[/noparse]

Gr,
Mightor

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| What the world needs is more geniuses with humility, there are so few of us left.
| "Wait...if that was a compliment, why is my fist of death tingling?"
| - Alice from Dilbert

Bean

Mightor,
Hey it was a good idea. But what spin calls an object is not what a OOP language calls an object. I'd say it's more like a library. So you cannot do polymorphism or anything like that with the normal spin "objects".

I have never seen that used, but I'm a delphi programmer. I'll have to try that in delphi and see if it works. Thanks for the insight.

Bean.

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·

Mightor

Bean (Hitt Consulting) said...
Mightor,
Hey it was a good idea. But what spin calls an object is not what a OOP language calls an object. I'd say it's more like a library. So you cannot do polymorphism or anything like that with the normal spin "objects".

I have never seen that used, but I'm a delphi programmer. I'll have to try that in delphi and see if it works. Thanks for the insight.

Bean.

Oh I wasn't looking to get as fancy as polymorphism, just a little reference to itself would've made me happy, haha.
One of the "best" examples in C++ is the use of the 'cout' object:

cout << "The value of foo is: " << foo << endl;

The << operator is overloaded and returns a reference to the cout object, allowing for the next << operator to make use of it [noparse]:)[/noparse] Looks simple and beautiful (in my eyes, that is). You can do this kind of thing in VB, C++ and probably Java, too. I have no idea if Delphi can do this, as I have never programmed that.

Gr,
Mightor

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| What the world needs is more geniuses with humility, there are so few of us left.
| "Wait...if that was a compliment, why is my fist of death tingling?"
| - Alice from Dilbert

deSilva

Returning function pointers is a piece of (non OOP) cake, IF you have the concept of function pointers at all. SPIN has not.

What I thought Mightor was looking for in his OP, was adding methods to an object by formal inheritance as in C++ or Java, or some ad-hoc means as available in JavaScript, PHP 4, etc.