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Enable user classes to override how Python.NET processes parameters of their functions #835

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c355bd6
introduced IPyArgumentConverter interface, that controls marshaling o…
lostmsu Mar 28, 2019
b5cae6c
enabled an ability to override Python to .NET argument coversion usin…
lostmsu Mar 28, 2019
bea9e0d
mentioned PyArgConverter in the CHANGELOG.md
lostmsu Mar 28, 2019
11a3ee6
fixed pyargconverter.cs not included into the older project file
lostmsu Mar 29, 2019
9c81661
moved default arg converter to its own file; cached converter lookup
lostmsu Apr 14, 2019
b6421e9
fixed defaultpyargconverter.cs not included in the older project file
lostmsu Apr 17, 2019
6cd7bd4
when looking for a custom argument converter look at base types too
lostmsu Jun 13, 2019
56ca4c9
a test to ensure it is possible to override argument conversion for i…
lostmsu Jun 13, 2019
7f894fa
fixed MarshallerOverride test
lostmsu Jun 20, 2019
aaafea8
fixed crash in MethodBinder.Bind when MethodInfo to invoke is passed …
lostmsu Aug 22, 2019
3804438
Merge branch 'master' into PR/PyArgConverter
lostmsu Feb 21, 2020
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moved default arg converter to its own file; cached converter lookup
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@lostmsu
lostmsu committed Jan 31, 2020
commit 9c81661fce5d33a587b7e2c94cdfa6bfdd87ad03
111 changes: 111 additions & 0 deletions src/runtime/defaultpyargconverter.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,111 @@
namespace Python.Runtime {
using System;

/// <summary>
/// The implementation of <see cref="T:Python.Runtime.IPyArgumentConverter" /> used by default
/// </summary>
public class DefaultPyArgumentConverter: IPyArgumentConverter
{
/// <summary>
/// Gets the singleton instance.
/// </summary>
public static DefaultPyArgumentConverter Instance { get; } = new DefaultPyArgumentConverter();

/// <inheritdoc />
/// <summary>
/// Attempts to convert an argument passed by Python to the specified parameter type.
/// </summary>
/// <param name="pyarg">Unmanaged pointer to the Python argument value</param>
/// <param name="parameterType">The expected type of the parameter</param>
/// <param name="needsResolution"><c>true</c> if the method is overloaded</param>
/// <param name="arg">This parameter will receive the converted value, matching the specified type</param>
/// <param name="isOut">This parameter will be set to <c>true</c>,
/// if the final type needs to be marshaled as an out argument.</param>
/// <returns><c>true</c>, if the object matches requested type,
/// and conversion was successful, otherwise <c>false</c></returns>
public virtual bool TryConvertArgument(
IntPtr pyarg, Type parameterType, bool needsResolution,
out object arg, out bool isOut)
{
arg = null;
isOut = false;
Type clrType = TryComputeClrArgumentType(parameterType, pyarg, needsResolution: needsResolution);
if (clrType == null)
{
return false;
}

if (!Converter.ToManaged(pyarg, clrType, out arg, false))
{
Exceptions.Clear();
return false;
}

isOut = clrType.IsByRef;
return true;
}

static Type TryComputeClrArgumentType(Type parameterType, IntPtr argument, bool needsResolution)
{
// this logic below handles cases when multiple overloading methods
// are ambiguous, hence comparison between Python and CLR types
// is necessary
Type clrType = null;
IntPtr pyArgType;
if (needsResolution)
{
// HACK: each overload should be weighted in some way instead
pyArgType = Runtime.PyObject_Type(argument);
Exceptions.Clear();
if (pyArgType != IntPtr.Zero)
{
clrType = Converter.GetTypeByAlias(pyArgType);
}
Runtime.XDecref(pyArgType);
}

if (clrType != null)
{
if ((parameterType != typeof(object)) && (parameterType != clrType))
{
IntPtr pyParamType = Converter.GetPythonTypeByAlias(parameterType);
pyArgType = Runtime.PyObject_Type(argument);
Exceptions.Clear();

bool typeMatch = false;
if (pyArgType != IntPtr.Zero && pyParamType == pyArgType)
{
typeMatch = true;
clrType = parameterType;
}
if (!typeMatch)
{
// this takes care of enum values
TypeCode argTypeCode = Type.GetTypeCode(parameterType);
TypeCode paramTypeCode = Type.GetTypeCode(clrType);
if (argTypeCode == paramTypeCode)
{
typeMatch = true;
clrType = parameterType;
}
}
Runtime.XDecref(pyArgType);
if (!typeMatch)
{
return null;
}
}
else
{
clrType = parameterType;
}
}
else
{
clrType = parameterType;
}

return clrType;
}
}
}
121 changes: 20 additions & 101 deletions src/runtime/methodbinder.cs
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Collections.Generic;
using System.Linq;

namespace Python.Runtime
{
using System.Linq;

/// <summary>
/// A MethodBinder encapsulates information about a (possibly overloaded)
/// managed method, and is responsible for selecting the right method given
Expand Down Expand Up @@ -180,14 +180,7 @@ IPyArgumentConverter GetArgumentConverter() {
Type converterType = null;
foreach (MethodBase method in this.methods)
{
var attribute = method.DeclaringType?
.GetCustomAttributes(typeof(PyArgConverterAttribute), inherit: false)
.OfType<PyArgConverterAttribute>()
.SingleOrDefault()
?? method.DeclaringType?.Assembly
.GetCustomAttributes(typeof(PyArgConverterAttribute), inherit: false)
.OfType<PyArgConverterAttribute>()
.SingleOrDefault();
PyArgConverterAttribute attribute = TryGetArgConverter(method.DeclaringType);
if (converterType == null)
{
if (attribute == null) continue;
Expand All @@ -203,6 +196,23 @@ IPyArgumentConverter GetArgumentConverter() {
return converter ?? DefaultPyArgumentConverter.Instance;
}

static readonly ConcurrentDictionary<Type, PyArgConverterAttribute> ArgConverterCache =
new ConcurrentDictionary<Type, PyArgConverterAttribute>();
static PyArgConverterAttribute TryGetArgConverter(Type type) {
if (type == null) return null;

return ArgConverterCache.GetOrAdd(type, declaringType =>
declaringType
.GetCustomAttributes(typeof(PyArgConverterAttribute), inherit: false)
.OfType<PyArgConverterAttribute>()
.SingleOrDefault()
?? declaringType.Assembly
.GetCustomAttributes(typeof(PyArgConverterAttribute), inherit: false)
.OfType<PyArgConverterAttribute>()
.SingleOrDefault()
);
}

/// <summary>
/// Precedence algorithm largely lifted from Jython - the concerns are
/// generally the same so we'll start with this and tweak as necessary.
Expand Down Expand Up @@ -481,97 +491,6 @@ object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
return margs;
}

internal static bool TryConvertArgument(IntPtr op, Type parameterType, bool needsResolution,
out object arg, out bool isOut)
{
arg = null;
isOut = false;
var clrtype = TryComputeClrArgumentType(parameterType, op, needsResolution: needsResolution);
if (clrtype == null)
{
return false;
}

if (!Converter.ToManaged(op, clrtype, out arg, false))
{
Exceptions.Clear();
return false;
}

isOut = clrtype.IsByRef;
return true;
}

static Type TryComputeClrArgumentType(Type parameterType, IntPtr argument, bool needsResolution)
{
// this logic below handles cases when multiple overloading methods
// are ambiguous, hence comparison between Python and CLR types
// is necessary
Type clrtype = null;
IntPtr pyoptype;
if (needsResolution)
{
// HACK: each overload should be weighted in some way instead
pyoptype = Runtime.PyObject_Type(argument);
Exceptions.Clear();
if (pyoptype != IntPtr.Zero)
{
clrtype = Converter.GetTypeByAlias(pyoptype);
}
Runtime.XDecref(pyoptype);
}

if (clrtype != null)
{
var typematch = false;
if ((parameterType != typeof(object)) && (parameterType != clrtype))
{
IntPtr pytype = Converter.GetPythonTypeByAlias(parameterType);
pyoptype = Runtime.PyObject_Type(argument);
Exceptions.Clear();
if (pyoptype != IntPtr.Zero)
{
if (pytype != pyoptype)
{
typematch = false;
}
else
{
typematch = true;
clrtype = parameterType;
}
}
if (!typematch)
{
// this takes care of enum values
TypeCode argtypecode = Type.GetTypeCode(parameterType);
TypeCode paramtypecode = Type.GetTypeCode(clrtype);
if (argtypecode == paramtypecode)
{
typematch = true;
clrtype = parameterType;
}
}
Runtime.XDecref(pyoptype);
if (!typematch)
{
return null;
}
}
else
{
typematch = true;
clrtype = parameterType;
}
}
else
{
clrtype = parameterType;
}

return clrtype;
}

static bool MatchesArgumentCount(int positionalArgumentCount, ParameterInfo[] parameters,
Dictionary<string, IntPtr> kwargDict,
out bool paramsArray,
Expand Down
30 changes: 0 additions & 30 deletions src/runtime/pyargconverter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,36 +21,6 @@ bool TryConvertArgument(IntPtr pyarg, Type parameterType,
bool needsResolution, out object arg, out bool isOut);
}

/// <summary>
/// The implementation of <see cref="IPyArgumentConverter"/> used by default
/// </summary>
public class DefaultPyArgumentConverter: IPyArgumentConverter {
/// <summary>
/// Gets the singleton instance.
/// </summary>
public static DefaultPyArgumentConverter Instance { get; } = new DefaultPyArgumentConverter();

/// <summary>
/// Attempts to convert an argument passed by Python to the specified parameter type.
/// </summary>
/// <param name="pyarg">Unmanaged pointer to the Python argument value</param>
/// <param name="parameterType">The expected type of the parameter</param>
/// <param name="needsResolution"><c>true</c> if the method is overloaded</param>
/// <param name="arg">This parameter will receive the converted value, matching the specified type</param>
/// <param name="isOut">This parameter will be set to <c>true</c>,
/// if the final type needs to be marshaled as an out argument.</param>
/// <returns><c>true</c>, if the object matches requested type,
/// and conversion was successful, otherwise <c>false</c></returns>
public virtual bool TryConvertArgument(
IntPtr pyarg, Type parameterType, bool needsResolution,
out object arg, out bool isOut)
{
return MethodBinder.TryConvertArgument(
pyarg, parameterType, needsResolution,
out arg, out isOut);
}
}

/// <summary>
/// Specifies an argument converter to be used, when methods in this class/assembly are called from Python.
/// </summary>
Expand Down