pythonnet/src/runtime/constructorbinding.cs at drop-python2 · filmor/pythonnet · GitHub

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using System;

using System.Reflection;

namespace Python.Runtime

{

/// <summary>

/// Implements a Python type that wraps a CLR ctor call. Constructor objects

/// support a .Overloads[] syntax to allow explicit ctor overload selection.

/// </summary>

/// <remarks>

/// ClassManager stores a ConstructorBinding instance in the class's __dict__['Overloads']

/// SomeType.Overloads[Type, ...] works like this:

/// 1) Python retrieves the Overloads attribute from this ClassObject's dictionary normally

/// and finds a non-null tp_descr_get slot which is called by the interpreter

/// and returns an IncRef()ed pyHandle to itself.

/// 2) The ConstructorBinding object handles the [] syntax in its mp_subscript by matching

/// the Type object parameters to a constructor overload using Type.GetConstructor()

/// [NOTE: I don't know why method overloads are not searched the same way.]

/// and creating the BoundContructor object which contains ContructorInfo object.

/// 3) In tp_call, if ctorInfo is not null, ctorBinder.InvokeRaw() is called.

/// </remarks>

internal class ConstructorBinding : ExtensionType

{

private Type type; // The managed Type being wrapped in a ClassObject

private IntPtr pyTypeHndl; // The python type tells GetInstHandle which Type to create.

private ConstructorBinder ctorBinder;

private IntPtr repr;

public ConstructorBinding(Type type, IntPtr pyTypeHndl, ConstructorBinder ctorBinder)

{

this.type = type;

Runtime.XIncref(pyTypeHndl);

this.pyTypeHndl = pyTypeHndl;

this.ctorBinder = ctorBinder;

repr = IntPtr.Zero;

}

/// <summary>

/// Descriptor __get__ implementation.

/// Implements a Python type that wraps a CLR ctor call that requires the use

/// of a .Overloads[pyTypeOrType...] syntax to allow explicit ctor overload

/// selection.

/// </summary>

/// <param name="op"> PyObject* to a Constructors wrapper </param>

/// <param name="instance">

/// the instance that the attribute was accessed through,

/// or None when the attribute is accessed through the owner

/// </param>

/// <param name="owner"> always the owner class </param>

/// <returns>

/// a CtorMapper (that borrows a reference to this python type and the

/// ClassObject's ConstructorBinder) wrapper.

/// </returns>

/// <remarks>

/// Python 2.6.5 docs:

/// object.__get__(self, instance, owner)

/// Called to get the attribute of the owner class (class attribute access)

/// or of an instance of that class (instance attribute access).

/// owner is always the owner class, while instance is the instance that

/// the attribute was accessed through, or None when the attribute is accessed through the owner.

/// This method should return the (computed) attribute value or raise an AttributeError exception.

/// </remarks>

public static IntPtr tp_descr_get(IntPtr op, IntPtr instance, IntPtr owner)

{

var self = (ConstructorBinding)GetManagedObject(op);

if (self == null)

{

return IntPtr.Zero;

}

// It doesn't seem to matter if it's accessed through an instance (rather than via the type).

/*if (instance != IntPtr.Zero) {

// This is ugly! PyObject_IsInstance() returns 1 for true, 0 for false, -1 for error...

if (Runtime.PyObject_IsInstance(instance, owner) < 1) {

return Exceptions.RaiseTypeError("How in the world could that happen!");

}

}*/

Runtime.XIncref(self.pyHandle);

return self.pyHandle;

}

/// <summary>

/// Implement explicit overload selection using subscript syntax ([]).

/// </summary>

/// <remarks>

/// ConstructorBinding.GetItem(PyObject *o, PyObject *key)

/// Return element of o corresponding to the object key or NULL on failure.

/// This is the equivalent of the Python expression o[key].

/// </remarks>

public static IntPtr mp_subscript(IntPtr op, IntPtr key)

{

var self = (ConstructorBinding)GetManagedObject(op);

Type[] types = Runtime.PythonArgsToTypeArray(key);

if (types == null)

{

return Exceptions.RaiseTypeError("type(s) expected");

}

//MethodBase[] methBaseArray = self.ctorBinder.GetMethods();

//MethodBase ci = MatchSignature(methBaseArray, types);

ConstructorInfo ci = self.type.GetConstructor(types);

if (ci == null)

{

return Exceptions.RaiseTypeError("No match found for constructor signature");

}

var boundCtor = new BoundContructor(self.type, self.pyTypeHndl, self.ctorBinder, ci);

return boundCtor.pyHandle;

}

/// <summary>

/// ConstructorBinding __repr__ implementation [borrowed from MethodObject].

/// </summary>

public static IntPtr tp_repr(IntPtr ob)

{

var self = (ConstructorBinding)GetManagedObject(ob);

if (self.repr != IntPtr.Zero)

{

Runtime.XIncref(self.repr);

return self.repr;

}

MethodBase[] methods = self.ctorBinder.GetMethods();

string name = self.type.FullName;

var doc = "";

foreach (MethodBase t in methods)

{

if (doc.Length > 0)

{

doc += "\n";

}

string str = t.ToString();

int idx = str.IndexOf("(");

doc += string.Format("{0}{1}", name, str.Substring(idx));

}

self.repr = Runtime.PyString_FromString(doc);

Runtime.XIncref(self.repr);

return self.repr;

}

/// <summary>

/// ConstructorBinding dealloc implementation.

/// </summary>

public new static void tp_dealloc(IntPtr ob)

{

var self = (ConstructorBinding)GetManagedObject(ob);

Runtime.XDecref(self.repr);

Runtime.XDecref(self.pyTypeHndl);

ExtensionType.FinalizeObject(self);

}

/// <summary>

/// Implements a Python type that constructs the given Type given a particular ContructorInfo.

/// </summary>

/// <remarks>

/// Here mostly because I wanted a new __repr__ function for the selected constructor.

/// An earlier implementation hung the __call__ on the ContructorBinding class and

/// returned an Incref()ed self.pyHandle from the __get__ function.

/// </remarks>

internal class BoundContructor : ExtensionType

{

private Type type; // The managed Type being wrapped in a ClassObject

private IntPtr pyTypeHndl; // The python type tells GetInstHandle which Type to create.

private ConstructorBinder ctorBinder;

private ConstructorInfo ctorInfo;

private IntPtr repr;

public BoundContructor(Type type, IntPtr pyTypeHndl, ConstructorBinder ctorBinder, ConstructorInfo ci)

{

this.type = type;

Runtime.XIncref(pyTypeHndl);

this.pyTypeHndl = pyTypeHndl;

this.ctorBinder = ctorBinder;

ctorInfo = ci;

repr = IntPtr.Zero;

}

/// <summary>

/// BoundContructor.__call__(PyObject *callable_object, PyObject *args, PyObject *kw)

/// </summary>

/// <param name="op"> PyObject *callable_object </param>

/// <param name="args"> PyObject *args </param>

/// <param name="kw"> PyObject *kw </param>

/// <returns> A reference to a new instance of the class by invoking the selected ctor(). </returns>

public static IntPtr tp_call(IntPtr op, IntPtr args, IntPtr kw)

{

var self = (BoundContructor)GetManagedObject(op);

// Even though a call with null ctorInfo just produces the old behavior

/*if (self.ctorInfo == null) {

string msg = "Usage: Class.Overloads[CLR_or_python_Type, ...]";

return Exceptions.RaiseTypeError(msg);

}*/

// Bind using ConstructorBinder.Bind and invoke the ctor providing a null instancePtr

// which will fire self.ctorInfo using ConstructorInfo.Invoke().

object obj = self.ctorBinder.InvokeRaw(IntPtr.Zero, args, kw, self.ctorInfo);

if (obj == null)

{

// XXX set an error

return IntPtr.Zero;

}

// Instantiate the python object that wraps the result of the method call

// and return the PyObject* to it.

return CLRObject.GetInstHandle(obj, self.pyTypeHndl);

}

/// <summary>

/// BoundContructor __repr__ implementation [borrowed from MethodObject].

/// </summary>

public static IntPtr tp_repr(IntPtr ob)

{

var self = (BoundContructor)GetManagedObject(ob);

if (self.repr != IntPtr.Zero)

{

Runtime.XIncref(self.repr);

return self.repr;

}

string name = self.type.FullName;

string str = self.ctorInfo.ToString();

int idx = str.IndexOf("(");

str = string.Format("returns a new {0}{1}", name, str.Substring(idx));

self.repr = Runtime.PyString_FromString(str);

Runtime.XIncref(self.repr);

return self.repr;

}

/// <summary>

/// ConstructorBinding dealloc implementation.

/// </summary>

public new static void tp_dealloc(IntPtr ob)

{

var self = (BoundContructor)GetManagedObject(ob);

Runtime.XDecref(self.repr);

Runtime.XDecref(self.pyTypeHndl);

FinalizeObject(self);

}

pythonnet/src/runtime/constructorbinding.cs at drop-python2 · filmor/pythonnet · GitHub

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