Values of Unknown Custom Attributes

[=?Utf-8?B?cGFnYXRlcw==?=]

Hello All,

I am sure that I am just overlooking something, but here's something I can't
quite get right...

I want to be able to get the value of a parameter of an unknown custom
attribute at runtime. All of the examples I have seen use casting of known
custom attributes to get these values.

Thanks,
pagates

[Nicholas Paldino [.NET/C# MVP]]

pagates,

Custom attributes are classes, they are not methods with parameters.
Getting any information from them using reflection is like using reflection
to get information from any other class. You have to have some expectation
of what you are looking for.

Can you provide an example of what you are trying to do?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"pagates" <pa*****@discus sions.microsoft .comwrote in message
news:17******** *************** ***********@mic rosoft.com...

Hello All,

I am sure that I am just overlooking something, but here's something I
can't
quite get right...

I want to be able to get the value of a parameter of an unknown custom
attribute at runtime. All of the examples I have seen use casting of
known
custom attributes to get these values.

Thanks,
pagates

[=?Utf-8?B?cGFnYXRlcw==?=]

Hi Nicholas,

Sure - it's a general question, but I wasn't sure how to word it...
Say I have something like this:
public class Class1
{
public Class1()
{
}

string _someProperty;
[ACustomAttribut e("Some Custom Attribute Value")]
public string SomeProperty
{
get { return _someProperty; }
set { _someProperty = value; }
}
}

I simply want to use reflection to get "Some Custom Attribute Value" from
the ACustomAttribut e attribute in a program that loads the assembly that
contains Class1. I can use GetCustomAttrib utes to get the attribute itself,
but I can't quite get how to get the value of the parameter contained therein.

Does that make sense? I can see what I want in my head, but getting it out
of there might be a problem.... : )

Thanks,
pagates
"Nicholas Paldino [.NET/C# MVP]" wrote:

pagates,

Custom attributes are classes, they are not methods with parameters.
Getting any information from them using reflection is like using reflection
to get information from any other class. You have to have some expectation
of what you are looking for.

Can you provide an example of what you are trying to do?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"pagates" <pa*****@discus sions.microsoft .comwrote in message
news:17******** *************** ***********@mic rosoft.com...

Hello All,

I am sure that I am just overlooking something, but here's something I
can't
quite get right...

I want to be able to get the value of a parameter of an unknown custom
attribute at runtime. All of the examples I have seen use casting of
known
custom attributes to get these values.

Thanks,
pagates

[Nicholas Paldino [.NET/C# MVP]]

pagates,

Ok, I understand now.

So, when you have the attribute like this:

[ACustomAttribut e("Some Custom Attribute Value")]
public string SomeProperty

The runtime constructs an instance of ACustomAttribut e passing the value
of "Some Custom Attribute Value". What the constructor does with this is up
to the attribute class. It's like any other class in this sense.
Typically, however, it will be exposed as a property. So, on the
ACustomAttribut e class, there should be some sort of property that exposes
the value. When you call GetCustomAttrib utes, you can cast the return value
to an instance of ACustomAttribut e and then access the property to get the
value (assuming it is exposed as such).
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"pagates" <pa*****@discus sions.microsoft .comwrote in message
news:D5******** *************** ***********@mic rosoft.com...

Hi Nicholas,

Sure - it's a general question, but I wasn't sure how to word it...
Say I have something like this:
public class Class1
{
public Class1()
{
}

string _someProperty;
[ACustomAttribut e("Some Custom Attribute Value")]
public string SomeProperty
{
get { return _someProperty; }
set { _someProperty = value; }
}
}

I simply want to use reflection to get "Some Custom Attribute Value" from
the ACustomAttribut e attribute in a program that loads the assembly that
contains Class1. I can use GetCustomAttrib utes to get the attribute
itself,
but I can't quite get how to get the value of the parameter contained
therein.

Does that make sense? I can see what I want in my head, but getting it
out
of there might be a problem.... : )

Thanks,
pagates
"Nicholas Paldino [.NET/C# MVP]" wrote:

>pagates,

Custom attributes are classes, they are not methods with parameters.
Getting any information from them using reflection is like using
reflection
to get information from any other class. You have to have some
expectation
of what you are looking for.

Can you provide an example of what you are trying to do?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"pagates" <pa*****@discus sions.microsoft .comwrote in message
news:17******* *************** ************@mi crosoft.com...

Hello All,

I am sure that I am just overlooking something, but here's something I
can't
quite get right...

I want to be able to get the value of a parameter of an unknown custom
attribute at runtime. All of the examples I have seen use casting of
known
custom attributes to get these values.

Thanks,
pagates

[bonk]

This approach is only possible if you can actually cast to the
CustomAttribute . If I reflect on an Assembly that also declares the
CustomAttribute Type I will not be able to cast to this Attribute type
because I do not reference that assembly. How could this issue be
solved ?

On Mar 29, 6:01 pm, "Nicholas Paldino [.NET/C# MVP]"
<[e-mail] d.caspershouse. comwrote:

pagates,

Ok, I understand now.

So, when you have theattributelik e this:

[ACustomAttribut e("Some CustomAttribute Value")]
public string SomeProperty

The runtime constructs an instance of ACustomAttribut e passing the value
of "Some CustomAttribute Value". What the constructor does with this is up
to theattributecla ss. It's like any other class in this sense.
Typically, however, it will be exposed as aproperty. So, on the
ACustomAttribut e class, there should be some sort ofpropertythat exposes
the value. When you call GetCustomAttrib utes, you can cast the return value
to an instance of ACustomAttribut e and then access thepropertytoge tthe
value (assuming it is exposed as such).

--
- Nicholas Paldino [.NET/C# MVP]
- [e-mail] .caspershouse.c om

"pagates" <paga...@discus sions.microsoft .comwrote in message

news:D5******** *************** ***********@mic rosoft.com...

Hi Nicholas,

Sure - it's a general question, but I wasn't sure how to word it...

Say I have something like this:
public class Class1
{
public Class1()
{
}

string _someProperty;
[ACustomAttribut e("Some CustomAttribute Value")]
public string SomeProperty
{
get{ return _someProperty; }
set { _someProperty = value; }
}
}

I simply want to usereflectionto get"Some CustomAttribute Value" from
the ACustomAttribut eattributein a program that loads the assembly that
contains Class1. I can use GetCustomAttrib utes togettheattribu te
itself,
but I can't quitegethow togetthe value of the parameter contained
therein.

Does that make sense? I can see what I want in my head, but getting it
out
of there might be a problem.... : )

Thanks,
pagates

"Nicholas Paldino [.NET/C# MVP]" wrote:

pagates,

Custom attributes are classes, they are not methods with parameters.
Getting any information from them usingreflection is like using
reflection
togetinformatio n from any other class. You have to have some
expectation
of what you are looking for.

Can you provide an example of what you are trying to do?

--
- Nicholas Paldino [.NET/C# MVP]
- [e-mail] .caspershouse.c om

"pagates" <paga...@discus sions.microsoft .comwrote in message
news:17******* *************** ************@mi crosoft.com...
Hello All,

I am sure that I am just overlooking something, but here's something I
can't
quitegetright.. .

I want to be able togetthe value of a parameter of an unknown custom
attributeat runtime. All of the examples I have seen use casting of
known
custom attributes togetthesevalue s.

Thanks,
pagates- Hide quoted text -

- Show quoted text -

[Marc Gravell]

Fist - you can't access *parameters*, but you can access *properties*;
and there-in lies the key.

If you don't want to reference the assembly, then perhaps use the
System.Componen tModel to access the values at runtime - i.e. (notepad
code; not compile-tested)

foreach(Attribu te untypedAttribut e in ...) { // presumably
GetAttributes() etc
Debug.WriteLine (untypedAttribu te.GetType().Na me);
foreach(Propert yDescriptor property in
TypeDescriptor. GetProperties(u ntypedAttribute )) {
Debug.WriteLine (string.Format( "{0}={1}", property.Name,
property.GetVal ue(untypedAttri bute)));
}
}

If you want to work with a *specific* attribute, then my first choice
would be to reference it! Otherwise, perhaps filter on FQN on
FullName.

Marc