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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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introduced IPyArgumentConverter interface, that controls marshaling o… 
…f Python objects when calling .NET methods
  • Loading branch information
@lostmsu
lostmsu committed Jan 31, 2020
commit c355bd6995487eb5d0c993821f97a02207290a4c
11 changes: 7 additions & 4 deletions src/runtime/methodbinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ internal class MethodBinder
public MethodBase[] methods;
public bool init = false;
public bool allow_threads = true;
readonly IPyArgumentConverter pyArgumentConverter = DefaultPyArgumentConverter.Instance;

internal MethodBinder()
{
Expand Down Expand Up @@ -326,7 +327,7 @@ internal Binding Bind(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, Meth
continue;
}
var outs = 0;
var margs = TryConvertArguments(pi, paramsArray, args, pynargs, kwargDict, defaultArgList,
var margs = this.TryConvertArguments(pi, paramsArray, args, pynargs, kwargDict, defaultArgList,
needsResolution: _methods.Length > 1,
outs: out outs);

Expand Down Expand Up @@ -382,7 +383,7 @@ internal Binding Bind(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, Meth
/// <param name="needsResolution"><c>true</c>, if overloading resolution is required</param>
/// <param name="outs">Returns number of output parameters</param>
/// <returns>An array of .NET arguments, that can be passed to a method.</returns>
static object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
IntPtr args, int pyArgCount,
Dictionary<string, IntPtr> kwargDict,
ArrayList defaultArgList,
Expand Down Expand Up @@ -423,7 +424,9 @@ static object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
}

bool isOut;
if (!TryConvertArgument(op, parameter.ParameterType, needsResolution, out margs[paramIndex], out isOut))
if (!this.pyArgumentConverter.TryConvertArgument(
op, parameter.ParameterType, needsResolution,
out margs[paramIndex], out isOut))
{
return null;
}
Expand All @@ -445,7 +448,7 @@ static object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
return margs;
}

static bool TryConvertArgument(IntPtr op, Type parameterType, bool needsResolution,
internal static bool TryConvertArgument(IntPtr op, Type parameterType, bool needsResolution,
out object arg, out bool isOut)
{
arg = null;
Expand Down
47 changes: 47 additions & 0 deletions src/runtime/pyargconverter.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
namespace Python.Runtime {
using System;

/// <summary>
/// Specifies how to convert Python objects, passed to .NET functions to the expected CLR types.
/// </summary>
public interface IPyArgumentConverter
{
/// <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>
bool TryConvertArgument(IntPtr pyarg, Type parameterType,
bool needsResolution, out object arg, out bool isOut);
}

public class DefaultPyArgumentConverter: IPyArgumentConverter {
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);
}
}
}