Question about C# after reading 3rd party library docs
Frederick C. Wilt
I am new to C# and .NET so bear with me if I don't use the correct terms.
I was writing a C# test app (in BDS2006) using this 3rd party library in a
.NET DLL. The documentation stated:
---------------------------------------
Note that when calling property read methods that require input parameters
using C#, "get_" must be appended to the property name. This is an
idiosyncrasy of the C# language and is not a naming convention inconsistency
within this API.
---------------------------------------
It seems to be the case and I was wondering why. Seems kind of odd to have
this requirement.
Regards, Frederick C. Wilt
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Joanna Carter [TeamB]
4510c1fc$1...@newsgroups.borland.com...
??????????????????!!!!!!!!!!!!!!!!
Interesting :-) I have been using C# for some time now and have never come
across any such convention.
The normal property declaration is :
class Thing
{
private string name;
public string Name
{
get { return name; }
set { name = value; }
}
}
However, the quote that you make says something about read methods that
require input parameters; the only thing I can see that satisifies that
would be an indexer (array property) :
class Thing
{
private Dictionary<string, Stuff> stuffList;
public Stuff this[string index]
{
get { return stuffList[index]; }
}
}
But in no case that I know of would you ever call the accessor method, which
does get compiled to a hidden method called something like get_Stuff.
Do the docs give any examples of what they are talking about ?
Joanna
--
Joanna Carter [TeamB]
Consultant Software Engineer
Frederick C. Wilt
Thanks for the feedback.
I verified that if I try to read from the property directly I get the
following error message (I have truncated the non-essential parts of the
message and changed the name of the property to a generic name):
>> [C# Error] WinForm.cs(260): Property, indexer, or event
>> 'SomePropertyName' is not supported by the language; try directly calling
>> accessor method...
Sure enough if I call get_SomePropertyName() with the appropriate parameters
everything is just fine.
I just think its rather odd that a new language like C# would not handle
properties of all sorts given that properties are not a new concept.
Regards, Frederick C. Wilt
"Joanna Carter [TeamB]" <joa...@not.for.spam> wrote in message
news:4510e002$1...@newsgroups.borland.com...
Joanna Carter [TeamB]
| >> [C# Error] WinForm.cs(260): Property, indexer, or event
| >> 'SomePropertyName' is not supported by the language; try directly
calling
| >> accessor method...
|
| Sure enough if I call get_SomePropertyName() with the appropriate
parameters
| everything is just fine.
|
| I just think its rather odd that a new language like C# would not handle
| properties of all sorts given that properties are not a new concept.
I think you will find that this is not a limitation of C#, but of the
language that the third-party assembly was written in. Take the time to
create your own small DLL in C# and try to use it from C#, you will find no
such problems.
Have another look at the documentation that you cited before :
| Note that when calling property read methods that require input parameters
At this point, I believe there should be a comma in the text, not after
"C#".
| using C#, "get_" must be appended to the property name.
The correct English word is prepended, not appended; I think this text is
written by a someone who has a poor command of English and that you need to
interpret it rather than read it :-)
| This is an idiosyncrasy of the C# language
This is just not true, full stop, period.
| and is not a naming convention inconsistency within this API.
Following on from mly last comment, this is also blatantly untrue.
If you have to call get_SomePropertyName(), then this is a function call,
not a property, the parentheses at the end indicate that this cannot be a
property.
My guess is that the language that this assembly was written in does not
support the concept of properties, insisting instead on the use of getter
and setter methods.
Is there any indication of the original language of the assembly ? I may be
totally wrong, but I thought that Delphi for .NET properties had to have
accessors named like this, but this shouldn't affect what is seen from
outside of an assembly.
Here is the IL for part of a class written in C# in an assembly that is used
from other assemblies
.class public abstract auto ansi beforefieldinit MyType
extends object
{
.property string Name
{
.get instance string Carter.Framework.MyType::get_Name()
}
...
.method public hidebysig specialname instance string get_Name() cil managed
{
.maxstack 1
.locals init (
[0] string text1)
L_0000: nop
L_0001: ldarg.0
L_0002: ldfld [mscorlib]System.Reflection.PropertyInfo
Carter.Framework.Property::info
L_0007: callvirt instance string
[mscorlib]System.Reflection.MemberInfo::get_Name()
L_000c: stloc.0
L_000d: br.s L_000f
L_000f: ldloc.0
L_0010: ret
}
So you can see that the IL knows about properties and links the property to
a getter method.
Here is the Delphi code for that.
public property Name: string read get_Name;
function Property.get_Name: string;
begin
Result := self.info.Name
end;
...and here is the C# code
public string Name
{
get
{
return this.info.Name;
}
}
...which you can see doesn't have the concept of a separated method.
But, much more telling is the MC++ code
public: __property System::String __gc* get_Name()
{
return this->info->Name;
}
My conclusion is that your DLL is written in Managed C++
Frederick C. Wilt
So when the error message says "not supported by the language" it is
referring to the language used for writing the 3rd party assembly and NOT
the C# language used for my test program?
That seems reasonable given your explanation.
Of course if it was written in managed C++ and is aimed at .NET users I have
to wonder why. All of the sample programs that came with the library are
written in C# or VB.NET.
So a message to the author seems to be in order.
Thanks for all the help, Frederick C. Wilt
"Joanna Carter [TeamB]" <joa...@not.for.spam> wrote in message
news:45118640$1...@newsgroups.borland.com...
Frederick C. Wilt
OK heard from the author and he states that the library was written using
VS2003/2005 and is a combination of C# code and VB.NET code.
So I am confused again.
Regards, Frederick C. Wilt
"Joanna Carter [TeamB]" <joa...@not.for.spam> wrote in message
news:45118640$1...@newsgroups.borland.com...
Joanna Carter [TeamB]
| OK heard from the author and he states that the library was written using
| VS2003/2005 and is a combination of C# code and VB.NET code.
Hmmm, if this is only one assembly, then I would doubt the mixture of
languages, as far as I know, it is only possible to have one language per
assembly.
| So I am confused again.
As am I. I am writing a massive application, parts of which are held in
various DLL assemblies, and I have *never* encountered this peculiarity.
Properties from any type in any assembly are always available by way of
simple property syntax from whatever calling assembly I could choose.
Can you say what the library is, or if not in public, would you like to let
me know privately; you've really got my curiosity up on this one :-)
Frederick C. Wilt
Do you have any tools that could delve inside the DLL file itself that might
provide insight? If the author has done something that has created this
situation I am sure he would like to be told about it. However being so new
to .NET this is currently out of my realm.
Sometimes I long for the simple days for CP/M. <g>
Thanks, Frederick C. Wilt
"Joanna Carter [TeamB]" <joa...@not.for.spam> wrote in message
news:4511...@newsgroups.borland.com...
Joanna Carter [TeamB]
| Do you have any tools that could delve inside the DLL file itself that
might
| provide insight? If the author has done something that has created this
| situation I am sure he would like to be told about it. However being so
new
| to .NET this is currently out of my realm.
I use Lutz Roeder's Reflector. It is free from
http://www.aisto.com/Roeder/DotNet/
If you are not sure what is involved in using it, if you want to send me the
DLL, I would be interested to take a peek :-)
Frederick C. Wilt
Just email your email address and I will provide the DLL. I will be
interested if you can help me understand what is going on.
Thank you, Frederick C. Wilt
David Clegg
> Just email your email address and I will provide the DLL. I will be
> interested if you can help me understand what is going on.
There are also some curious bystanders who would be interested in
hearing the results of your and Joanna's discoveries :-)
--
Cheers,
David Clegg
dcl...@gmail.com
http://cc.borland.com/Author.aspx?ID=72299
QualityCentral. The best way to bug Borland about bugs.
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Craig Stuntz [TeamB]
> Is there any indication of the original language of the assembly ? I
> may be totally wrong, but I thought that Delphi for .NET properties
> had to have accessors named like this, but this shouldn't affect what
> is seen from outside of an assembly.
.NET requires that accessors are named this way. C# accessors don't
have names in the code, so the C# compiler generates them under the
hood, as your IL example demonstrates. Delphi doesn't require that you
use this naming convention, but will generate .NET-compliant accessors
using this convention if you do not.
--
Craig Stuntz [TeamB] · Vertex Systems Corp. · Columbus, OH
Delphi/InterBase Weblog : http://blogs.teamb.com/craigstuntz
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