[Python.NET] issue disambiguating overloaded method that takes an array

Discussion:

Adrian Perez

2011-05-17 01:29:36 UTC

Hello everyone,

This is probably a total n00b question, but I've been using pythonnet in our toolchain to communicate with a private c# assembly for months now without ever running into a problem I couldn't eventually figure out. This one has me totally stumped, and I'm hoping something obvious will jump out at experienced eyes.

(I did a find/replace for secrecy, besides silly names these are the raw results I get back)

accessor= MyCompany.SomeNamespace.SomeTypeArrayAccessor
accessor.WriteByte.__overloads__

Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Byte[])
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Byte[], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32, System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32, Byte[], Int32 ByRef)

desired_method= accessor.WriteByte.__overloads__[MyCompany.SomeNamespace.SomeType, System.Array[System.Byte]]
arg_a= ...
arg_b= ...
type(arg_a)

type(arg_b)

result= desired_method(arg_a, arg_b)

Traceback (most recent call last):
File "<string>", line 1, in <fragment>
TypeError: No method matches given arguments

Does anyone see the obvious thing I'm doing wrong? Disambiguating can be a pain but I've done it before for other methods and have never had such an impossible time getting the correct method called.

Thanks,

Adrian Perez
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Barton

2011-05-17 07:38:21 UTC

Permalink

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def TestCharArray():
from System import Array
charArrType = Array[Char]
##arrType = charArrType('hello')
##for char in arrType:
## print char,
## Also works on instances of the type! ##
strCharArr = s.__overloads__[charArrType]
s = strCharArr(list('hello'))
print s

Post by Adrian Perez
Hello everyone,
This is probably a total n00b question, but I've been using pythonnet in our toolchain to communicate with a private c# assembly for months now without ever running into a problem I couldn't eventually figure out. This one has me totally stumped, and I'm hoping something obvious will jump out at experienced eyes.
(I did a find/replace for secrecy, besides silly names these are the raw results I get back)

accessor= MyCompany.SomeNamespace.SomeTypeArrayAccessor
accessor.WriteByte.__overloads__

desired_method= accessor.WriteByte.__overloads__[MyCompany.SomeNamespace.SomeType, System.Array[System.Byte]]
arg_a= ...
arg_b= ...
type(arg_a)

type(arg_b)

result= desired_method(arg_a, arg_b)

File "<string>", line 1, in<fragment>
TypeError: No method matches given arguments
Does anyone see the obvious thing I'm doing wrong? Disambiguating can be a pain but I've done it before for other methods and have never had such an impossible time getting the correct method called.
Thanks,
Adrian Perez
_________________________________________________
http://mail.python.org/mailman/listinfo/pythondotnet

_________________________________________________
Python.NET mailing list - PythonDotNet-+ZN9ApsXKcEdnm+***@public.gmane.org
http://mail.python.org/mailman/listinfo/pythondotnet

Adrian Perez

2011-05-17 17:18:01 UTC

Permalink

Thank you for the snippets. I had poured over the unit tests and seen similar examples of how to do this already, but two commentless replies inspired me to trace through this in a debugger.

The issue ended up being that I was erroneously under the impression I was calling a static method, and was retrieving the method off of the 'type' object, rather than an instance of the type. The error you get back is the generic "no method matches given arguments", because my local 'desired_method' expected an initial 'self' argument, and so silently took 'arg_a' to be 'self'. This meant MethodBinder.Bind() only thought it had 1 input argument and could not match it to any of the overloads.

Cheers,

Adrian Perez

-----Original Message-----
From: BCline [mailto:bcline3078-***@public.gmane.org]
Sent: Tuesday, May 17, 2011 12:56 AM
Cc: Adrian Perez; pythondotnet-+ZN9ApsXKcEdnm+***@public.gmane.org
Subject: Re: [Python.NET] issue disambiguating overloaded method UPDATE

from System import String, Char, Int32
def TestCharArray():
from System import Array
charArrType = Array[Char]
##arrType = charArrType('hello')
##for char in arrType:
## print char,
## Also works on instances of the type! ##
strCharArr = String.__overloads__[charArrType]
s = strCharArr(list('hello'))
print s
TestCharArray()

Post by Barton
from System import Array
charArrType = Array[Char]
##arrType = charArrType('hello')
## print char,
## Also works on instances of the type! ##
strCharArr = s.__overloads__[charArrType]
s = strCharArr(list('hello'))
print s

Post by Adrian Perez
Hello everyone,
This is probably a total n00b question, but I've been using pythonnet
in our toolchain to communicate with a private c# assembly for months
now without ever running into a problem I couldn't eventually figure
out. This one has me totally stumped, and I'm hoping something
obvious will jump out at experienced eyes.
(I did a find/replace for secrecy, besides silly names these are the
raw results I get back)
A C# class exposes a method 'WriteByte' that has 5 overloads (note

accessor= MyCompany.SomeNamespace.SomeTypeArrayAccessor
accessor.WriteByte.__overloads__

Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Byte[]) Boolean
WriteByte(MyCompany.SomeNamespace.SomeType, Byte[], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType,
System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32,
System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32, Byte[], Int32 ByRef)

desired_method=
accessor.WriteByte.__overloads__[MyCompany.SomeNamespace.SomeType,
System.Array[System.Byte]]

The problem may be right here - if I print out desired_method.__doc__
I get the same 5 methods listed above. Anyway, then I compute my
arguments, and can verify they have the types I expect (If it
matters, arg_b is created by a call to

arg_a= ...
arg_b= ...
type(arg_a)

type(arg_b)

<class 'System.Byte[]'>
However, when I try to call the disambiguated method with the correct

result= desired_method(arg_a, arg_b)

File "<string>", line 1, in<fragment>
TypeError: No method matches given arguments
Does anyone see the obvious thing I'm doing wrong? Disambiguating
can be a pain but I've done it before for other methods and have
never had such an impossible time getting the correct method called.
Thanks,
Adrian Perez
_________________________________________________
http://mail.python.org/mailman/listinfo/pythondotnet

_________________________________________________
Python.NET mailing list - PythonDotNet-+ZN9ApsXKcEdnm+***@public.gmane.org
http://mail.python.org/mailman/listinfo/pythondotnet

BCline

2011-05-17 07:56:14 UTC

Permalink

from System import String, Char, Int32
def TestCharArray():
from System import Array
charArrType = Array[Char]
##arrType = charArrType('hello')
##for char in arrType:
## print char,
## Also works on instances of the type! ##
strCharArr = String.__overloads__[charArrType]
s = strCharArr(list('hello'))
print s
TestCharArray()

Post by Adrian Perez
Hello everyone,
This is probably a total n00b question, but I've been using pythonnet
in our toolchain to communicate with a private c# assembly for months
now without ever running into a problem I couldn't eventually figure
out. This one has me totally stumped, and I'm hoping something
obvious will jump out at experienced eyes.
(I did a find/replace for secrecy, besides silly names these are the
raw results I get back)
A C# class exposes a method 'WriteByte' that has 5 overloads (note

accessor= MyCompany.SomeNamespace.SomeTypeArrayAccessor
accessor.WriteByte.__overloads__

Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Byte[])
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Byte[], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType,
System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32,
System.Collections.Generic.IEnumerable`1[System.Byte], Int32 ByRef)
Boolean WriteByte(MyCompany.SomeNamespace.SomeType, Int32, Byte[], Int32 ByRef)

desired_method=
accessor.WriteByte.__overloads__[MyCompany.SomeNamespace.SomeType,
System.Array[System.Byte]]

arg_a= ...
arg_b= ...
type(arg_a)

type(arg_b)

<class 'System.Byte[]'>
However, when I try to call the disambiguated method with the correct

result= desired_method(arg_a, arg_b)

File "<string>", line 1, in<fragment>
TypeError: No method matches given arguments
Does anyone see the obvious thing I'm doing wrong? Disambiguating
can be a pain but I've done it before for other methods and have
never had such an impossible time getting the correct method called.
Thanks,
Adrian Perez
_________________________________________________
http://mail.python.org/mailman/listinfo/pythondotnet

_________________________________________________
Python.NET mailing list - PythonDotNet-+ZN9ApsXKcEdnm+***@public.gmane.org
http://mail.python.org/mailman/listinfo/pythondotnet