Re: [Python.NET] Memory Type Problems

[Barton]

__overloads__ has been deprecated for some time now. I prefer the IP compatible Overloads. >>> import clr >>> from System import Int32 >>> help(Int32)  |  ----------------------------------------------------------------------  |  Data and other attributes defined here:  |   |  __new__ = <built-in method __new__ of CLR Metatype object>  |      T.__new__(S, ...) -> a new object with type S, a subtype of T  |   |  ----------------------------------------------------------------------  |  Data descriptors inherited from Object:  |   |  Finalize  |      Void Finalize()  |   |  GetType  |      System.Type GetType()  |   |  MemberwiseClone  |      System.Object MemberwiseClone()  |   |  Overloads  |   |  ReferenceEquals  |      Boolean ReferenceEquals(System.Object, System.Object)  |   |  __overloads__ As for the smarts behind it, it'll be fun to get back into the guts and see if some improvements can be made. Oh boy; I just love those System.NotSupportedException(s)! Thanks for the feedback. On 01/15/2013 12:38 AM, Jeffrey Bush wrote: Thanks for all your input! With your help I have been able to get everything working as expected. Getting the address of a string with ctypes was a bit trickier than I expected, but I the end the following works (if anyone would like to know):     import ctypes     from System import IntPtr     addr = ctypes.cast(ctypes.c_char_p(s), ctypes.c_void_p).value     ptr = IntPtr.[long](addr) That is for "str" objects. As a side note these should be treated as read-only due to Python optimizations with strings. For things that come from ctypes.create_string_bufffer() the ctypes.c_char_p(s) should be just s. These are not read-only. The last thing I would like to suggest to make things more "wrist friendly" as you put it is to make the need for __overloads__ less by making it smarter. Two examples come to mind. First is the example above. If I try IntPtr(5) or IntPtr(5L) it complains that "'int/long' value cannot be converted to System.IntPtr". It seems like it is trying to cast or something instead of call the constructor. Or maybe since ints and longs are both ValueTypes it can't choose which to use. Or maybe even just the fact they use the same number of arguments. Another example is later on when I am using Memory objects from my code. The Memory class is abstract and has two concrete implementations: ManagedMemory and UnmanagedMemory. I was trying to call a method that takes either one of these three along with any type of array of value-types. In this case all of Python crashes when it tries to convert the UnmanagedMemory object to an array (exception text is at the end of this message). This is something that should be determinable by the .NET bridge. For now I won't be needing to write much more than I have using Python for .NET, however it would be nice to make the system a little smarter with overloads. Thanks for the great work so far! Jeff Exception that crashes Python: Unhandled Exception: System.NotSupportedException: Cannot create arrays of TypedReference, ArgIterator, ByRef, or RuntimeArgumentHandle Objects.    at System.Array.InternalCreate(Void* elementType, Int32 rank, Int32* pLengths, Int32* pLowerBounds)    at System.Array.CreateInstance(Type elementType, Int32 length)    at Python.Runtime.Converter.ToArray(IntPtr value, Type obType, Object& result, Boolean setError) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\converter.cs:line 648    at Python.Runtime.Converter.ToManagedValue(IntPtr value, Type obType, Object& result, Boolean set Error) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\converter.cs:line 263    at Python.Runtime.Converter.ToManaged(IntPtr value, Type type, Object& result, Boolean setError) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\converter.cs:line 201    at Python.Runtime.MethodBinder.Bind(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, MethodInfo[] methodinfo) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\methodbinder.cs:line 278    at Python.Runtime.MethodBinder.Invoke(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, MethodInfo[] methodinfo) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\methodbinder.cs:line 340    at Python.Runtime.MethodObject.Invoke(IntPtr target, IntPtr args, IntPtr kw, MethodBase info) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\methodobject.cs:line 63    at Python.Runtime.MethodBinding.tp_call(IntPtr ob, IntPtr args, IntPtr kw) in D:\Users\Barton\Documents\Visual Studio 2010\Projects\PySharp\trunk\pythonnet\src\runtime\methodbinding.cs:line 135 On Tue, Jan 8, 2013 at 7:19 AM, Bradley Friedman <b...@fie.us> wrote: You can construct .net intptr objects from ints.  So you need the address. You already provided the solution to that. In python, you get memory addresses by using ctypes.  Be careful to handle it in a way that will support both 32 and 64 bit binaries. Sent from my iPad On Jan 8, 2013, at 4:51 AM, Barton <bar...@bcdesignswell.com> wrote: 1) Not being much of a C guy myself, I'm not sure what to make of all this pointer business.      Especially since the object reference is capable of being indexed (and SO much more [>>> help(a)])         - Just don't try a.Address(0) like I just did - got a core dump on Mono - 2) C# type rules apply (except that python lets you try things like "a == input"); underneath Array.Equals(System.Array) is called.         hence Int32(7) == 7 is false.             - I tend to think of this package as a "wrist-friendly" (see Boo) wrapper over the Mono/.NET components more than a trying to be a type compatibility layer. 3) Slicing seems like something that is worth implementing. That would take a lot of typing out of     Array.Copy(a1, srcIndx, a2, dstIndx, len) Great fun, Barton On 01/08/2013 12:31 AM, Jeffrey Bush wrote: How about my other questions? Pass as a pointer (like ctypes would do)? Convert that pointer back? And I don't seem to be able to get the slices (":") to work with byte arrays. Thanks for the help getting the byte arrays started though. I am able to take the output from reading a file and send it right to the array constructor: import clr from System import Array, Byte with open("file.txt", 'rb') as f: input = f.read() a = Array[Byte](input) One problem though is that equality doesn't work (a==input is False). But maybe this is because one is a list of (unsigned) bytes and one is a list of (signed) characters. a[0] and input[0] display differently. Jeff  On Sat, Jan 5, 2013 at 2:07 PM, Barton <bar...@bcdesignswell.com> wrote: Definitely more useful: >>> import clr >>> from System import Array, Byte >>> g = (0 for i in range(10)) >>> a = Array[Byte](list(i for i in g)) >>> a[5] 0 On 01/04/2013 06:33 PM, Jeffrey Bush wrote: Hi, I have a library in C for compression. I made Python script for testing it, called using ctypes. Now, I am working on a .NET library for something very similar and would like to test it in the same way. However, I am getting lost in how to do some of the things with your library. The function I need to call looks like: public static long Compress(Memory input, Memory output) The Memory class is a wrapper around either managed byte arrays, void* (for efficiency), or memory mapped files. This allows a unified system for accessing general chunks of memory regardless if they are managed, native, or on the filesystem. They are created through static functions: public static Memory From(MemoryStream s, bool all = true) public static Memory From(byte[] b, bool readOnly = false) public static Memory From(byte[] b, long offset, long size, bool readOnly = false) public unsafe static Memory From(UnmanagedMemoryStream s, bool all = true) public unsafe static Memory From(void* b, long size, bool readOnly = false) public unsafe static Memory From(IntPtr b, long size, bool readOnly = false) public static Memory FromFile(string file, bool readOnly = false) public static Memory OfSize(long size) The only ones I can easily use are the last two (OfSize and FromFile). I have not yet figured out how to call the other ones properly. I don't seem to be able to allocate byte arrays with Array[Byte](10), it complains that 10 cannot be converted to System.Byte[] so it seems that it believes I am casting instead of creating a new array. No overloads seem to exist. So now here are my questions and the ctypes answer: How do I construct a byte array? (ctypes.create_string_buffer) How do I take a Python list/array and pass it as a pointer? (ctypes has this conversion happen automatically) How do I turn a byte array into a useful Python list/array? As-is I can't use the Python-style indexers (except negative numbers). (The ctypes buffer works directly as a list, but also supports ".raw" and ".value") How do I convert a pointer into a useful Python list/array? (ctypes casting allows this to work) Last point, although this is probably a limitation of .NET, but just to make sure. The default argument values can't be used, but it is possible that this isn't even in the assembly information and only works for source in the same module. Thanks, Jeff _________________________________________________ Python.NET mailing list - PythonDotNet@python.org http://mail.python.org/mailman/listinfo/pythondotnet _________________________________________________ Python.NET mailing list - PythonDotNet@python.org http://mail.python.org/mailman/listinfo/pythondotnet _________________________________________________ Python.NET mailing list - PythonDotNet@python.org http://mail.python.org/mailman/listinfo/pythondotnet

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