No pointers to objects!?
BlitzMax Forums/BlitzMax Beginners Area/No pointers to objects!?
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| Hmm I was wanting to do some networks of connected objects and was shocked to find that Bmax uses no pointers for objects. I wanted to have a sort of web where each object knows it's parent and each object knows children. In this way networks could be connected or merged together. Why does Bmax not support object pointers? Pointers are really one of the keystones of OOP... |
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Isn't what you are trying to achieve covered by being able to do stuff like the following?...SuperStrict Graphics 800,600 Type TThing Field nextTThing:TThing Field prevTTHing:TThing Field value:Int End Type Local thingA:TThing = New TTHing Local thingB:TThing = New TThing thingB.value = 123 thingA.nextTThing = thingB DrawText thingA.nextTThing.value,10,10 Flip WaitKey That you can do such without seeing an * or -> is one of the nice things about the language, I think. |
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| Well sort of. You see storing copies entire objects rather than simple pointers is not very memory efficient from what I understand. I have some rather large objects and to store 5 copies of each object in another object is really not the best option. Unless they are passed by reference. |
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They are -- two New statements, two objects:SuperStrict Graphics 800,600 Type TThing Field nextTThing:TThing Field prevTTHing:TThing Field value:Int End Type Local thingA:TThing = New TTHing Local thingB:TThing = New TThing thingA.nextTThing = thingB thingB.value = 123 DrawText thingA.nextTThing.value,10,10 thingA.nextTThing.value = 321 DrawText thingB.value,10,30 Flip WaitKey Given what you can do with pretty much any order of language these days, I'd say that having to explicitly denote references is what makes C/C++ irrevocably mid-level whereas not having to is what defines BMax as high level (and readable). Be aware, though, that the circular references will befuddle the garbage collector so null/update the appropriate fields when you attempt to release one of those objects. |
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| Ryan, nextTThing and prevTThing are Object References (very similar to the references used in JAVA, C# and C++) and not Copies of Objects. References are much more save to use than pointers, but give you pretty much of all the fuctionality of pointers. |
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| Yeah as the others have said BMax does have object pointers. Every time you say ThisThing: TThing = ThatThing you are making a pointer, not a copy. |
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| Following on from potential GC issues: Note also that you have a TList class and that you can maintain a list as a (static) class variable and that there are methods in the associated TLink class to find the next and previous entries in the list. Hence you don't necessarily need to maintain next and previous references as fields. |
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| ...and was shocked to find that Bmax uses no pointers for objects. I'd be shocked if anyone actually bothered to read the docs. The second and third lines of 'Language>Objects' reads... Objects are handled by reference. This means that the actual memory used by an object to store its data is shared between all the variables that refer to that object. This makes objects very efficient to deal with, as assigning an object to a variable simply involves assigning a reference to the object - not an entire object. Passing objects to functions and returning objects from functions is also very efficient as again only references need to be copied. |
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