On May 16, 2006, at 12:20 PM, Dan Stenning wrote:
DO you mean I can use Ptr as a datatype in Structs?
Certainly; you can use it anywhere you like. The idea of a declare-
only type went away in RB 5.5.
1) when using Addressof to point to an RB function, does the ptr
work fine
with C++ ( I presume so since its intended as a callback )
Yes, that's exactly what it's for.
2) can I point to class instance methods or am I limited to global
functions
in modules?
You can use shared methods or module methods as callbacks, but not,
generally speaking, instance methods.
3) am I free to copy the pointer to an int , using casting etc ?
Yes, you can cast a ptr to an integer, and vice versa.
4) can I do integer calculations etc? Ie can I add an index to the
pointer?
You can add an offset to the pointer, yes, but that's the only
arithmetic operator allowed.
5) saw this in your release notes: the ability to dereference it
(ptr) with
any structure-safe type : how does this work ?
Dim foo As Ptr
Dim bar As Integer
foo.Integer = 42
bar = foo.Integer
You can use the name of any structure-safe type in place of "Integer"
to peek or poke a value of the appropriate type from the ptr's target.
6) also : "There is an optional byte offset parameter" could you
explain
this ?
Dim foo As Ptr
Dim bar As Boolean
foo.Boolean( 6 ) = True
bar = foo.Boolean( 6 )
You can pass an optional integer parameter to the "method call",
which is a byte offset from the pointer itself.
7) is it ok, allowable to pass/use Ptr as an argument datatype in RB
methods and functions ?
Sure.
Mars Saxman
REAL Software
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