Baby's First Garbage Collector

Re:Baby's First Garbage Collector by MichaelGG on Sunday December 08, 2013 @08:31PM (#6872423)

C# can also use managed pointers (type& instead of type*). All out/ref parameters use this type of pointer, and it'll get updated by the runtime, like an object reference - no pinning necessary.

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Re:Baby's First Garbage Collector by kevingadd on Sunday December 08, 2013 @10:24PM (#6872700)

Interesting, can you link to an example of their use? I've never seen them in the documentation or examples, but I remember that Managed C++ and C++/CLI have something similar.

Or are you just saying that you can 'use' them via out/ref? I interpreted your post to mean that you can store them in fields, which would be stellar but seems like it would break reference lifetime guarantees.

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Re:Baby's First Garbage Collector by MichaelGG on Monday December 09, 2013 @01:09PM (#6875665)

You only use them via out/ref. Section 13.4.2 of the CLI spec says:

- Managed pointers can be passed as arguments, stored in local variables, and returned as values.

- Managed pointers cannot be stored in static variables, array elements, or fields of objects or value types.

So you're right, they have very limited scope as it'd be messy otherwise. It's my understanding that the JVM does not have pointers even at this level, hence Java can't do out/ref parameters. (Sure, tuples are a better way to handle many cases of out params, but sometimes a well chosen ref can really be nicer.)

I think C++ also uses the term "managed pointer" but not in the same technical sense (I think it just means reference.) Using "safe" C++/CLI generation limits the scope of pointers just like we'd expect.

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