CSharp VB Excel COM Differences

[Alan Roberts]

Can someone please explain the following for me...

I am trying to link to a .NET DLL from Excel. Excel needs to pass a
reference to itself to the DLL and then the DLL needs to perform some work
on the running instance of Excel via that reference. As an example, a VB
DLL to return the path to the current active workbook contains the following
(in addition to the COM GUIDS automatically added to a new COMClass)...

Public Class Class1
Public Sub New()
MyBase.New()
End Sub
Private gExcel As Object
Public Property Excel() As Object
Set(ByVal value As Object)
gExcel = value
End Set
Get
Excel = gExcel
End Get
End Property
Public Function Path() As String
Return Excel.ThisWorkb ook.Path
End Function
End Class

After adding a refernece to the DLL, a macro in Excel could call this as
follows

Sub VBTest()
Dim VBTest As New VBExcelTest.Cla ss1
Set VBTest.Excel = Application
Debug.Print VBTest.Path
End Sub

This all work fine

How can I do the same thing using C#? If I try to create a DLL with
equivalent(?) code eg

public class Class1
{
public Class1(){
}
private object gExcel;
public object Excel{
get{
return gExcel;
}
set{
gExcel = value;
}
}
public string Path(){
return Excel.ThisWorkb ook.Path;
}
}

I get a compile error saying that - 'object' does not contain a definition
for 'ThisWorkbook'

How can I get this to work?

Thanks

Alan

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

Re: CSharp VB Excel COM Differences

Alan,

The reason this works in VB is that the VB compiler will translate
property and method calls on variables of type object to be reflection
calls, which cause your code to work.

Unfortunately, C# doesn't support this functionality. You will have to
use reflection to get the member names and then invoke them like that.

OR, you could set a reference to the interop assemblies for Excel, and
cast the object passed into your method into one of those classes in the
interop assembly. This would prevent you from having to do any late
binding.

Also, you should be careful of the operations you are performing. When
you call methods on any object in Excel, you are creating a runtime callable
wrapper which should be disposed of if you aren't using it anymore. In the
case of your Path property, you should assign the result of ThisWorkbook to
a variable, then pass that to the static ReleaseComObjec t method on the
Marshal class.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m

"Alan Roberts" <alan@statistix l.co.uk> wrote in message
news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..[color=blue]
> Can someone please explain the following for me...
>
> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
> reference to itself to the DLL and then the DLL needs to perform some work
> on the running instance of Excel via that reference. As an example, a VB
> DLL to return the path to the current active workbook contains the
> following (in addition to the COM GUIDS automatically added to a new
> COMClass)...
>
> Public Class Class1
> Public Sub New()
> MyBase.New()
> End Sub
> Private gExcel As Object
> Public Property Excel() As Object
> Set(ByVal value As Object)
> gExcel = value
> End Set
> Get
> Excel = gExcel
> End Get
> End Property
> Public Function Path() As String
> Return Excel.ThisWorkb ook.Path
> End Function
> End Class
>
> After adding a refernece to the DLL, a macro in Excel could call this as
> follows
>
> Sub VBTest()
> Dim VBTest As New VBExcelTest.Cla ss1
> Set VBTest.Excel = Application
> Debug.Print VBTest.Path
> End Sub
>
> This all work fine
>
> How can I do the same thing using C#? If I try to create a DLL with
> equivalent(?) code eg
>
> public class Class1
> {
> public Class1(){
> }
> private object gExcel;
> public object Excel{
> get{
> return gExcel;
> }
> set{
> gExcel = value;
> }
> }
> public string Path(){
> return Excel.ThisWorkb ook.Path;
> }
> }
>
> I get a compile error saying that - 'object' does not contain a definition
> for 'ThisWorkbook'
>
> How can I get this to work?
>
> Thanks
>
> Alan
>[/color]

[Alan Roberts]

Re: CSharp VB Excel COM Differences

Hi Nicholas, thanks for the thorough reply! Does this mean that the
following simple VB code to calculate the sum of the values specified in an
Excel Range object

Public Function Sum(ByVal range As String) As Double
Dim i, j As Integer
Dim total As Double
For i = 1 To Excel.Range(ran ge).Rows.Count
For j = 1 To Excel.Range(ran ge).Columns.Cou nt
total = total + Convert.ToDoubl e(Excel.Range(r ange).cells(i,
j).value)
Next j
Next i
Return total
End Function


must become something like this in C#???


public double Sum(string range)
{
object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
object[] Parameters;
double total= 0;
Parameters = new Object[1];
Parameters[0] = range;
oRange = Excel.GetType() .InvokeMember(" Range", BindingFlags.Ge tProperty,
null, Excel, Parameters);
oRows = oRange.GetType( ).InvokeMember( "Rows", BindingFlags.Ge tProperty,
null, oRange, null);
oRowCount = oRows.GetType() .InvokeMember(" Count",
BindingFlags.Ge tProperty, null, oRows, null);
oCols = oRange.GetType( ).InvokeMember( "Columns",
BindingFlags.Ge tProperty, null, oRange, null);
oColCount = oCols.GetType() .InvokeMember(" Count",
BindingFlags.Ge tProperty, null, oCols, null);
for (int i = 1; i <= (int)oColCount; i++)
{
for (int j = 1; j <= (int)oRowCount; j++)
{
Parameters = new Object[2];
Parameters[0] = j;
Parameters[1] = i;
oValue = new Object();
oCell = new Object();
oCell = oRange.GetType( ).InvokeMember( "Cells",
BindingFlags.Ge tProperty, null, oRange, Parameters);
oValue = oCell.GetType() .InvokeMember(" Value",
BindingFlags.Ge tProperty, null, oCell, null);
total += (double)oValue;
}
}
return total;
}


Or is there a better way?

Thanks

Alan



"Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote in
message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...[color=blue]
> Alan,
>
> The reason this works in VB is that the VB compiler will translate
> property and method calls on variables of type object to be reflection
> calls, which cause your code to work.
>
> Unfortunately, C# doesn't support this functionality. You will have to
> use reflection to get the member names and then invoke them like that.
>
> OR, you could set a reference to the interop assemblies for Excel, and
> cast the object passed into your method into one of those classes in the
> interop assembly. This would prevent you from having to do any late
> binding.
>
> Also, you should be careful of the operations you are performing. When
> you call methods on any object in Excel, you are creating a runtime
> callable wrapper which should be disposed of if you aren't using it
> anymore. In the case of your Path property, you should assign the result
> of ThisWorkbook to a variable, then pass that to the static
> ReleaseComObjec t method on the Marshal class.
>
> Hope this helps.
>
>
> --
> - Nicholas Paldino [.NET/C# MVP]
> - mvp@spam.guard. caspershouse.co m
>
> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..[color=green]
>> Can someone please explain the following for me...
>>
>> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
>> reference to itself to the DLL and then the DLL needs to perform some
>> work on the running instance of Excel via that reference. As an example,
>> a VB DLL to return the path to the current active workbook contains the
>> following (in addition to the COM GUIDS automatically added to a new
>> COMClass)...
>>
>> Public Class Class1
>> Public Sub New()
>> MyBase.New()
>> End Sub
>> Private gExcel As Object
>> Public Property Excel() As Object
>> Set(ByVal value As Object)
>> gExcel = value
>> End Set
>> Get
>> Excel = gExcel
>> End Get
>> End Property
>> Public Function Path() As String
>> Return Excel.ThisWorkb ook.Path
>> End Function
>> End Class
>>
>> After adding a refernece to the DLL, a macro in Excel could call this as
>> follows
>>
>> Sub VBTest()
>> Dim VBTest As New VBExcelTest.Cla ss1
>> Set VBTest.Excel = Application
>> Debug.Print VBTest.Path
>> End Sub
>>
>> This all work fine
>>
>> How can I do the same thing using C#? If I try to create a DLL with
>> equivalent(?) code eg
>>
>> public class Class1
>> {
>> public Class1(){
>> }
>> private object gExcel;
>> public object Excel{
>> get{
>> return gExcel;
>> }
>> set{
>> gExcel = value;
>> }
>> }
>> public string Path(){
>> return Excel.ThisWorkb ook.Path;
>> }
>> }
>>
>> I get a compile error saying that - 'object' does not contain a
>> definition for 'ThisWorkbook'
>>
>> How can I get this to work?
>>
>> Thanks
>>
>> Alan
>>[/color]
>
>[/color]

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

Re: CSharp VB Excel COM Differences

Alan,

Yes, it's something like that. You could cut down on some of the
reflection calls, but not by much.

Also, you need to call ReleaseComObjec t for each object you expose. For
example, in your Sum method, you need to release the result returned from:

Excel.Range - Returns a collection of ranges
Excel.Range(ran ge) - Returns the individual range.
Excel.Range(ran ge).Rows - Returns the collection of ranges.
Excel.Range(ran ge).Columns - Returns the collection of columns
Excel.Range(ran ge).Cells - Returns the collection of cells.
Excel.Range(ran ge).Cells(i, j) - Returns the range representing the
individual cell.

All of those need to have their references released properly.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m

"Alan Roberts" <alan@statistix l.co.uk> wrote in message
news:u50iW68BGH A.412@TK2MSFTNG P15.phx.gbl...[color=blue]
> Hi Nicholas, thanks for the thorough reply! Does this mean that the
> following simple VB code to calculate the sum of the values specified in
> an Excel Range object
>
> Public Function Sum(ByVal range As String) As Double
> Dim i, j As Integer
> Dim total As Double
> For i = 1 To Excel.Range(ran ge).Rows.Count
> For j = 1 To Excel.Range(ran ge).Columns.Cou nt
> total = total + Convert.ToDoubl e(Excel.Range(r ange).cells(i,
> j).value)
> Next j
> Next i
> Return total
> End Function
>
>
> must become something like this in C#???
>
>
> public double Sum(string range)
> {
> object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
> object[] Parameters;
> double total= 0;
> Parameters = new Object[1];
> Parameters[0] = range;
> oRange = Excel.GetType() .InvokeMember(" Range",
> BindingFlags.Ge tProperty, null, Excel, Parameters);
> oRows = oRange.GetType( ).InvokeMember( "Rows", BindingFlags.Ge tProperty,
> null, oRange, null);
> oRowCount = oRows.GetType() .InvokeMember(" Count",
> BindingFlags.Ge tProperty, null, oRows, null);
> oCols = oRange.GetType( ).InvokeMember( "Columns",
> BindingFlags.Ge tProperty, null, oRange, null);
> oColCount = oCols.GetType() .InvokeMember(" Count",
> BindingFlags.Ge tProperty, null, oCols, null);
> for (int i = 1; i <= (int)oColCount; i++)
> {
> for (int j = 1; j <= (int)oRowCount; j++)
> {
> Parameters = new Object[2];
> Parameters[0] = j;
> Parameters[1] = i;
> oValue = new Object();
> oCell = new Object();
> oCell = oRange.GetType( ).InvokeMember( "Cells",
> BindingFlags.Ge tProperty, null, oRange, Parameters);
> oValue = oCell.GetType() .InvokeMember(" Value",
> BindingFlags.Ge tProperty, null, oCell, null);
> total += (double)oValue;
> }
> }
> return total;
> }
>
>
> Or is there a better way?
>
> Thanks
>
> Alan
>
>
>
> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote
> in message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...[color=green]
>> Alan,
>>
>> The reason this works in VB is that the VB compiler will translate
>> property and method calls on variables of type object to be reflection
>> calls, which cause your code to work.
>>
>> Unfortunately, C# doesn't support this functionality. You will have
>> to use reflection to get the member names and then invoke them like that.
>>
>> OR, you could set a reference to the interop assemblies for Excel, and
>> cast the object passed into your method into one of those classes in the
>> interop assembly. This would prevent you from having to do any late
>> binding.
>>
>> Also, you should be careful of the operations you are performing.
>> When you call methods on any object in Excel, you are creating a runtime
>> callable wrapper which should be disposed of if you aren't using it
>> anymore. In the case of your Path property, you should assign the result
>> of ThisWorkbook to a variable, then pass that to the static
>> ReleaseComObjec t method on the Marshal class.
>>
>> Hope this helps.
>>
>>
>> --
>> - Nicholas Paldino [.NET/C# MVP]
>> - mvp@spam.guard. caspershouse.co m
>>
>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..[color=darkred]
>>> Can someone please explain the following for me...
>>>
>>> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
>>> reference to itself to the DLL and then the DLL needs to perform some
>>> work on the running instance of Excel via that reference. As an
>>> example, a VB DLL to return the path to the current active workbook
>>> contains the following (in addition to the COM GUIDS automatically added
>>> to a new COMClass)...
>>>
>>> Public Class Class1
>>> Public Sub New()
>>> MyBase.New()
>>> End Sub
>>> Private gExcel As Object
>>> Public Property Excel() As Object
>>> Set(ByVal value As Object)
>>> gExcel = value
>>> End Set
>>> Get
>>> Excel = gExcel
>>> End Get
>>> End Property
>>> Public Function Path() As String
>>> Return Excel.ThisWorkb ook.Path
>>> End Function
>>> End Class
>>>
>>> After adding a refernece to the DLL, a macro in Excel could call this as
>>> follows
>>>
>>> Sub VBTest()
>>> Dim VBTest As New VBExcelTest.Cla ss1
>>> Set VBTest.Excel = Application
>>> Debug.Print VBTest.Path
>>> End Sub
>>>
>>> This all work fine
>>>
>>> How can I do the same thing using C#? If I try to create a DLL with
>>> equivalent(?) code eg
>>>
>>> public class Class1
>>> {
>>> public Class1(){
>>> }
>>> private object gExcel;
>>> public object Excel{
>>> get{
>>> return gExcel;
>>> }
>>> set{
>>> gExcel = value;
>>> }
>>> }
>>> public string Path(){
>>> return Excel.ThisWorkb ook.Path;
>>> }
>>> }
>>>
>>> I get a compile error saying that - 'object' does not contain a
>>> definition for 'ThisWorkbook'
>>>
>>> How can I get this to work?
>>>
>>> Thanks
>>>
>>> Alan
>>>[/color]
>>
>>[/color]
>
>[/color]

[Alan Roberts]

Re: CSharp VB Excel COM Differences

Blimey! Thanks a lot Nicholas. I guess I will stick with VB for now. On
the whole I find C# more elegant but VB seems better suited to this
particular application.

Thanks

Alan

"Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote in
message news:edpv$VFCGH A.916@TK2MSFTNG P10.phx.gbl...[color=blue]
> Alan,
>
> Yes, it's something like that. You could cut down on some of the
> reflection calls, but not by much.
>
> Also, you need to call ReleaseComObjec t for each object you expose.
> For example, in your Sum method, you need to release the result returned
> from:
>
> Excel.Range - Returns a collection of ranges
> Excel.Range(ran ge) - Returns the individual range.
> Excel.Range(ran ge).Rows - Returns the collection of ranges.
> Excel.Range(ran ge).Columns - Returns the collection of columns
> Excel.Range(ran ge).Cells - Returns the collection of cells.
> Excel.Range(ran ge).Cells(i, j) - Returns the range representing the
> individual cell.
>
> All of those need to have their references released properly.
>
> Hope this helps.
>
>
> --
> - Nicholas Paldino [.NET/C# MVP]
> - mvp@spam.guard. caspershouse.co m
>
> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> news:u50iW68BGH A.412@TK2MSFTNG P15.phx.gbl...[color=green]
>> Hi Nicholas, thanks for the thorough reply! Does this mean that the
>> following simple VB code to calculate the sum of the values specified in
>> an Excel Range object
>>
>> Public Function Sum(ByVal range As String) As Double
>> Dim i, j As Integer
>> Dim total As Double
>> For i = 1 To Excel.Range(ran ge).Rows.Count
>> For j = 1 To Excel.Range(ran ge).Columns.Cou nt
>> total = total + Convert.ToDoubl e(Excel.Range(r ange).cells(i,
>> j).value)
>> Next j
>> Next i
>> Return total
>> End Function
>>
>>
>> must become something like this in C#???
>>
>>
>> public double Sum(string range)
>> {
>> object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
>> object[] Parameters;
>> double total= 0;
>> Parameters = new Object[1];
>> Parameters[0] = range;
>> oRange = Excel.GetType() .InvokeMember(" Range",
>> BindingFlags.Ge tProperty, null, Excel, Parameters);
>> oRows = oRange.GetType( ).InvokeMember( "Rows",
>> BindingFlags.Ge tProperty, null, oRange, null);
>> oRowCount = oRows.GetType() .InvokeMember(" Count",
>> BindingFlags.Ge tProperty, null, oRows, null);
>> oCols = oRange.GetType( ).InvokeMember( "Columns",
>> BindingFlags.Ge tProperty, null, oRange, null);
>> oColCount = oCols.GetType() .InvokeMember(" Count",
>> BindingFlags.Ge tProperty, null, oCols, null);
>> for (int i = 1; i <= (int)oColCount; i++)
>> {
>> for (int j = 1; j <= (int)oRowCount; j++)
>> {
>> Parameters = new Object[2];
>> Parameters[0] = j;
>> Parameters[1] = i;
>> oValue = new Object();
>> oCell = new Object();
>> oCell = oRange.GetType( ).InvokeMember( "Cells",
>> BindingFlags.Ge tProperty, null, oRange, Parameters);
>> oValue = oCell.GetType() .InvokeMember(" Value",
>> BindingFlags.Ge tProperty, null, oCell, null);
>> total += (double)oValue;
>> }
>> }
>> return total;
>> }
>>
>>
>> Or is there a better way?
>>
>> Thanks
>>
>> Alan
>>
>>
>>
>> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote
>> in message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...[color=darkred]
>>> Alan,
>>>
>>> The reason this works in VB is that the VB compiler will translate
>>> property and method calls on variables of type object to be reflection
>>> calls, which cause your code to work.
>>>
>>> Unfortunately, C# doesn't support this functionality. You will have
>>> to use reflection to get the member names and then invoke them like
>>> that.
>>>
>>> OR, you could set a reference to the interop assemblies for Excel,
>>> and cast the object passed into your method into one of those classes in
>>> the interop assembly. This would prevent you from having to do any late
>>> binding.
>>>
>>> Also, you should be careful of the operations you are performing.
>>> When you call methods on any object in Excel, you are creating a runtime
>>> callable wrapper which should be disposed of if you aren't using it
>>> anymore. In the case of your Path property, you should assign the
>>> result of ThisWorkbook to a variable, then pass that to the static
>>> ReleaseComObjec t method on the Marshal class.
>>>
>>> Hope this helps.
>>>
>>>
>>> --
>>> - Nicholas Paldino [.NET/C# MVP]
>>> - mvp@spam.guard. caspershouse.co m
>>>
>>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>>> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..
>>>> Can someone please explain the following for me...
>>>>
>>>> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
>>>> reference to itself to the DLL and then the DLL needs to perform some
>>>> work on the running instance of Excel via that reference. As an
>>>> example, a VB DLL to return the path to the current active workbook
>>>> contains the following (in addition to the COM GUIDS automatically
>>>> added to a new COMClass)...
>>>>
>>>> Public Class Class1
>>>> Public Sub New()
>>>> MyBase.New()
>>>> End Sub
>>>> Private gExcel As Object
>>>> Public Property Excel() As Object
>>>> Set(ByVal value As Object)
>>>> gExcel = value
>>>> End Set
>>>> Get
>>>> Excel = gExcel
>>>> End Get
>>>> End Property
>>>> Public Function Path() As String
>>>> Return Excel.ThisWorkb ook.Path
>>>> End Function
>>>> End Class
>>>>
>>>> After adding a refernece to the DLL, a macro in Excel could call this
>>>> as follows
>>>>
>>>> Sub VBTest()
>>>> Dim VBTest As New VBExcelTest.Cla ss1
>>>> Set VBTest.Excel = Application
>>>> Debug.Print VBTest.Path
>>>> End Sub
>>>>
>>>> This all work fine
>>>>
>>>> How can I do the same thing using C#? If I try to create a DLL with
>>>> equivalent(?) code eg
>>>>
>>>> public class Class1
>>>> {
>>>> public Class1(){
>>>> }
>>>> private object gExcel;
>>>> public object Excel{
>>>> get{
>>>> return gExcel;
>>>> }
>>>> set{
>>>> gExcel = value;
>>>> }
>>>> }
>>>> public string Path(){
>>>> return Excel.ThisWorkb ook.Path;
>>>> }
>>>> }
>>>>
>>>> I get a compile error saying that - 'object' does not contain a
>>>> definition for 'ThisWorkbook'
>>>>
>>>> How can I get this to work?
>>>>
>>>> Thanks
>>>>
>>>> Alan
>>>>
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

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

Re: CSharp VB Excel COM Differences

Alan,

The problem still exists in VB. In VB, the RCW for all of the objects I
list out still are out there, and you don't release them.

The only thing that VB makes easier is having to actually make the
calls, it will make it easy to perfrom the reflection for you, but not the
actuall calls to ReleaseComObjec t.


--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m

"Alan Roberts" <alan@statistix l.co.uk> wrote in message
news:uQob93ICGH A.216@TK2MSFTNG P15.phx.gbl...[color=blue]
> Blimey! Thanks a lot Nicholas. I guess I will stick with VB for now. On
> the whole I find C# more elegant but VB seems better suited to this
> particular application.
>
> Thanks
>
> Alan
>
> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote
> in message news:edpv$VFCGH A.916@TK2MSFTNG P10.phx.gbl...[color=green]
>> Alan,
>>
>> Yes, it's something like that. You could cut down on some of the
>> reflection calls, but not by much.
>>
>> Also, you need to call ReleaseComObjec t for each object you expose.
>> For example, in your Sum method, you need to release the result returned
>> from:
>>
>> Excel.Range - Returns a collection of ranges
>> Excel.Range(ran ge) - Returns the individual range.
>> Excel.Range(ran ge).Rows - Returns the collection of ranges.
>> Excel.Range(ran ge).Columns - Returns the collection of columns
>> Excel.Range(ran ge).Cells - Returns the collection of cells.
>> Excel.Range(ran ge).Cells(i, j) - Returns the range representing the
>> individual cell.
>>
>> All of those need to have their references released properly.
>>
>> Hope this helps.
>>
>>
>> --
>> - Nicholas Paldino [.NET/C# MVP]
>> - mvp@spam.guard. caspershouse.co m
>>
>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>> news:u50iW68BGH A.412@TK2MSFTNG P15.phx.gbl...[color=darkred]
>>> Hi Nicholas, thanks for the thorough reply! Does this mean that the
>>> following simple VB code to calculate the sum of the values specified in
>>> an Excel Range object
>>>
>>> Public Function Sum(ByVal range As String) As Double
>>> Dim i, j As Integer
>>> Dim total As Double
>>> For i = 1 To Excel.Range(ran ge).Rows.Count
>>> For j = 1 To Excel.Range(ran ge).Columns.Cou nt
>>> total = total + Convert.ToDoubl e(Excel.Range(r ange).cells(i,
>>> j).value)
>>> Next j
>>> Next i
>>> Return total
>>> End Function
>>>
>>>
>>> must become something like this in C#???
>>>
>>>
>>> public double Sum(string range)
>>> {
>>> object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
>>> object[] Parameters;
>>> double total= 0;
>>> Parameters = new Object[1];
>>> Parameters[0] = range;
>>> oRange = Excel.GetType() .InvokeMember(" Range",
>>> BindingFlags.Ge tProperty, null, Excel, Parameters);
>>> oRows = oRange.GetType( ).InvokeMember( "Rows",
>>> BindingFlags.Ge tProperty, null, oRange, null);
>>> oRowCount = oRows.GetType() .InvokeMember(" Count",
>>> BindingFlags.Ge tProperty, null, oRows, null);
>>> oCols = oRange.GetType( ).InvokeMember( "Columns",
>>> BindingFlags.Ge tProperty, null, oRange, null);
>>> oColCount = oCols.GetType() .InvokeMember(" Count",
>>> BindingFlags.Ge tProperty, null, oCols, null);
>>> for (int i = 1; i <= (int)oColCount; i++)
>>> {
>>> for (int j = 1; j <= (int)oRowCount; j++)
>>> {
>>> Parameters = new Object[2];
>>> Parameters[0] = j;
>>> Parameters[1] = i;
>>> oValue = new Object();
>>> oCell = new Object();
>>> oCell = oRange.GetType( ).InvokeMember( "Cells",
>>> BindingFlags.Ge tProperty, null, oRange, Parameters);
>>> oValue = oCell.GetType() .InvokeMember(" Value",
>>> BindingFlags.Ge tProperty, null, oCell, null);
>>> total += (double)oValue;
>>> }
>>> }
>>> return total;
>>> }
>>>
>>>
>>> Or is there a better way?
>>>
>>> Thanks
>>>
>>> Alan
>>>
>>>
>>>
>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote
>>> in message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...
>>>> Alan,
>>>>
>>>> The reason this works in VB is that the VB compiler will translate
>>>> property and method calls on variables of type object to be reflection
>>>> calls, which cause your code to work.
>>>>
>>>> Unfortunately, C# doesn't support this functionality. You will have
>>>> to use reflection to get the member names and then invoke them like
>>>> that.
>>>>
>>>> OR, you could set a reference to the interop assemblies for Excel,
>>>> and cast the object passed into your method into one of those classes
>>>> in the interop assembly. This would prevent you from having to do any
>>>> late binding.
>>>>
>>>> Also, you should be careful of the operations you are performing.
>>>> When you call methods on any object in Excel, you are creating a
>>>> runtime callable wrapper which should be disposed of if you aren't
>>>> using it anymore. In the case of your Path property, you should assign
>>>> the result of ThisWorkbook to a variable, then pass that to the static
>>>> ReleaseComObjec t method on the Marshal class.
>>>>
>>>> Hope this helps.
>>>>
>>>>
>>>> --
>>>> - Nicholas Paldino [.NET/C# MVP]
>>>> - mvp@spam.guard. caspershouse.co m
>>>>
>>>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>>>> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..
>>>>> Can someone please explain the following for me...
>>>>>
>>>>> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
>>>>> reference to itself to the DLL and then the DLL needs to perform some
>>>>> work on the running instance of Excel via that reference. As an
>>>>> example, a VB DLL to return the path to the current active workbook
>>>>> contains the following (in addition to the COM GUIDS automatically
>>>>> added to a new COMClass)...
>>>>>
>>>>> Public Class Class1
>>>>> Public Sub New()
>>>>> MyBase.New()
>>>>> End Sub
>>>>> Private gExcel As Object
>>>>> Public Property Excel() As Object
>>>>> Set(ByVal value As Object)
>>>>> gExcel = value
>>>>> End Set
>>>>> Get
>>>>> Excel = gExcel
>>>>> End Get
>>>>> End Property
>>>>> Public Function Path() As String
>>>>> Return Excel.ThisWorkb ook.Path
>>>>> End Function
>>>>> End Class
>>>>>
>>>>> After adding a refernece to the DLL, a macro in Excel could call this
>>>>> as follows
>>>>>
>>>>> Sub VBTest()
>>>>> Dim VBTest As New VBExcelTest.Cla ss1
>>>>> Set VBTest.Excel = Application
>>>>> Debug.Print VBTest.Path
>>>>> End Sub
>>>>>
>>>>> This all work fine
>>>>>
>>>>> How can I do the same thing using C#? If I try to create a DLL with
>>>>> equivalent(?) code eg
>>>>>
>>>>> public class Class1
>>>>> {
>>>>> public Class1(){
>>>>> }
>>>>> private object gExcel;
>>>>> public object Excel{
>>>>> get{
>>>>> return gExcel;
>>>>> }
>>>>> set{
>>>>> gExcel = value;
>>>>> }
>>>>> }
>>>>> public string Path(){
>>>>> return Excel.ThisWorkb ook.Path;
>>>>> }
>>>>> }
>>>>>
>>>>> I get a compile error saying that - 'object' does not contain a
>>>>> definition for 'ThisWorkbook'
>>>>>
>>>>> How can I get this to work?
>>>>>
>>>>> Thanks
>>>>>
>>>>> Alan
>>>>>
>>>>
>>>>
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

[Alan Roberts]

Re: CSharp VB Excel COM Differences

Thanks Nicholas. I guess I am still having dificulties with the Release
idea....
I have come up with the following routine in C#


private static object GetProperty(obj ect obj, string sProperty)
{
string[] Properties = sProperty.Split (new char[] {'.'});
object oProp;
oProp = obj;
for (int i = 0; i <= Properties.GetU pperBound(0); i++)
{
if (Properties[i].Contains("("))
oProp = oProp.GetType() .InvokeMember(P roperties[i].Substring(0,
Properties[i].IndexOf('(')),
BindingFlags.Ge tProperty, null, oProp,
Properties[i].Substring(Prop erties[i].IndexOf('(')
+ 1, Properties[i].IndexOf(')') - (Properties[i].IndexOf('(') +
1)).Split(new char[] { ','
}));
else
oProp = oProp.GetType() .InvokeMember(P roperties[i],
BindingFlags.Ge tProperty, null,
oProp, null);
}

return oProp;
}


basically it simplifies my code as I once I have a link to the Excel object
I can access properties using code along the lines of
GetProperty(oEx cel, "ActiveSheet.Ce lls(1,1).Value" );
rather than having all of the step by step code I presented previousle.

If I use this function in a routine to calculate the total of a range of
cells eg


double total = 0;
for (int i = 1; i <= 5; i++)
{
total += (double)GetProp erty(oRange, "Cells(" + i.ToString() +",
1").Value");
}


What objects do I have to release both in the for loop code above and in the
GetProperty function that it calls?

Thanks for your help with this

Alan



"Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote in
message news:eaTawxpCGH A.2036@TK2MSFTN GP14.phx.gbl...[color=blue]
> Alan,
>
> The problem still exists in VB. In VB, the RCW for all of the objects
> I list out still are out there, and you don't release them.
>
> The only thing that VB makes easier is having to actually make the
> calls, it will make it easy to perfrom the reflection for you, but not the
> actuall calls to ReleaseComObjec t.
>
>
> --
> - Nicholas Paldino [.NET/C# MVP]
> - mvp@spam.guard. caspershouse.co m
>
> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> news:uQob93ICGH A.216@TK2MSFTNG P15.phx.gbl...[color=green]
>> Blimey! Thanks a lot Nicholas. I guess I will stick with VB for now.
>> On the whole I find C# more elegant but VB seems better suited to this
>> particular application.
>>
>> Thanks
>>
>> Alan
>>
>> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote
>> in message news:edpv$VFCGH A.916@TK2MSFTNG P10.phx.gbl...[color=darkred]
>>> Alan,
>>>
>>> Yes, it's something like that. You could cut down on some of the
>>> reflection calls, but not by much.
>>>
>>> Also, you need to call ReleaseComObjec t for each object you expose.
>>> For example, in your Sum method, you need to release the result returned
>>> from:
>>>
>>> Excel.Range - Returns a collection of ranges
>>> Excel.Range(ran ge) - Returns the individual range.
>>> Excel.Range(ran ge).Rows - Returns the collection of ranges.
>>> Excel.Range(ran ge).Columns - Returns the collection of columns
>>> Excel.Range(ran ge).Cells - Returns the collection of cells.
>>> Excel.Range(ran ge).Cells(i, j) - Returns the range representing the
>>> individual cell.
>>>
>>> All of those need to have their references released properly.
>>>
>>> Hope this helps.
>>>
>>>
>>> --
>>> - Nicholas Paldino [.NET/C# MVP]
>>> - mvp@spam.guard. caspershouse.co m
>>>
>>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>>> news:u50iW68BGH A.412@TK2MSFTNG P15.phx.gbl...
>>>> Hi Nicholas, thanks for the thorough reply! Does this mean that the
>>>> following simple VB code to calculate the sum of the values specified
>>>> in an Excel Range object
>>>>
>>>> Public Function Sum(ByVal range As String) As Double
>>>> Dim i, j As Integer
>>>> Dim total As Double
>>>> For i = 1 To Excel.Range(ran ge).Rows.Count
>>>> For j = 1 To Excel.Range(ran ge).Columns.Cou nt
>>>> total = total + Convert.ToDoubl e(Excel.Range(r ange).cells(i,
>>>> j).value)
>>>> Next j
>>>> Next i
>>>> Return total
>>>> End Function
>>>>
>>>>
>>>> must become something like this in C#???
>>>>
>>>>
>>>> public double Sum(string range)
>>>> {
>>>> object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
>>>> object[] Parameters;
>>>> double total= 0;
>>>> Parameters = new Object[1];
>>>> Parameters[0] = range;
>>>> oRange = Excel.GetType() .InvokeMember(" Range",
>>>> BindingFlags.Ge tProperty, null, Excel, Parameters);
>>>> oRows = oRange.GetType( ).InvokeMember( "Rows",
>>>> BindingFlags.Ge tProperty, null, oRange, null);
>>>> oRowCount = oRows.GetType() .InvokeMember(" Count",
>>>> BindingFlags.Ge tProperty, null, oRows, null);
>>>> oCols = oRange.GetType( ).InvokeMember( "Columns",
>>>> BindingFlags.Ge tProperty, null, oRange, null);
>>>> oColCount = oCols.GetType() .InvokeMember(" Count",
>>>> BindingFlags.Ge tProperty, null, oCols, null);
>>>> for (int i = 1; i <= (int)oColCount; i++)
>>>> {
>>>> for (int j = 1; j <= (int)oRowCount; j++)
>>>> {
>>>> Parameters = new Object[2];
>>>> Parameters[0] = j;
>>>> Parameters[1] = i;
>>>> oValue = new Object();
>>>> oCell = new Object();
>>>> oCell = oRange.GetType( ).InvokeMember( "Cells",
>>>> BindingFlags.Ge tProperty, null, oRange, Parameters);
>>>> oValue = oCell.GetType() .InvokeMember(" Value",
>>>> BindingFlags.Ge tProperty, null, oCell, null);
>>>> total += (double)oValue;
>>>> }
>>>> }
>>>> return total;
>>>> }
>>>>
>>>>
>>>> Or is there a better way?
>>>>
>>>> Thanks
>>>>
>>>> Alan
>>>>
>>>>
>>>>
>>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om>
>>>> wrote in message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...
>>>>> Alan,
>>>>>
>>>>> The reason this works in VB is that the VB compiler will translate
>>>>> property and method calls on variables of type object to be reflection
>>>>> calls, which cause your code to work.
>>>>>
>>>>> Unfortunately, C# doesn't support this functionality. You will
>>>>> have to use reflection to get the member names and then invoke them
>>>>> like that.
>>>>>
>>>>> OR, you could set a reference to the interop assemblies for Excel,
>>>>> and cast the object passed into your method into one of those classes
>>>>> in the interop assembly. This would prevent you from having to do any
>>>>> late binding.
>>>>>
>>>>> Also, you should be careful of the operations you are performing.
>>>>> When you call methods on any object in Excel, you are creating a
>>>>> runtime callable wrapper which should be disposed of if you aren't
>>>>> using it anymore. In the case of your Path property, you should
>>>>> assign the result of ThisWorkbook to a variable, then pass that to the
>>>>> static ReleaseComObjec t method on the Marshal class.
>>>>>
>>>>> Hope this helps.
>>>>>
>>>>>
>>>>> --
>>>>> - Nicholas Paldino [.NET/C# MVP]
>>>>> - mvp@spam.guard. caspershouse.co m
>>>>>
>>>>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
>>>>> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..
>>>>>> Can someone please explain the following for me...
>>>>>>
>>>>>> I am trying to link to a .NET DLL from Excel. Excel needs to pass a
>>>>>> reference to itself to the DLL and then the DLL needs to perform some
>>>>>> work on the running instance of Excel via that reference. As an
>>>>>> example, a VB DLL to return the path to the current active workbook
>>>>>> contains the following (in addition to the COM GUIDS automatically
>>>>>> added to a new COMClass)...
>>>>>>
>>>>>> Public Class Class1
>>>>>> Public Sub New()
>>>>>> MyBase.New()
>>>>>> End Sub
>>>>>> Private gExcel As Object
>>>>>> Public Property Excel() As Object
>>>>>> Set(ByVal value As Object)
>>>>>> gExcel = value
>>>>>> End Set
>>>>>> Get
>>>>>> Excel = gExcel
>>>>>> End Get
>>>>>> End Property
>>>>>> Public Function Path() As String
>>>>>> Return Excel.ThisWorkb ook.Path
>>>>>> End Function
>>>>>> End Class
>>>>>>
>>>>>> After adding a refernece to the DLL, a macro in Excel could call this
>>>>>> as follows
>>>>>>
>>>>>> Sub VBTest()
>>>>>> Dim VBTest As New VBExcelTest.Cla ss1
>>>>>> Set VBTest.Excel = Application
>>>>>> Debug.Print VBTest.Path
>>>>>> End Sub
>>>>>>
>>>>>> This all work fine
>>>>>>
>>>>>> How can I do the same thing using C#? If I try to create a DLL with
>>>>>> equivalent(?) code eg
>>>>>>
>>>>>> public class Class1
>>>>>> {
>>>>>> public Class1(){
>>>>>> }
>>>>>> private object gExcel;
>>>>>> public object Excel{
>>>>>> get{
>>>>>> return gExcel;
>>>>>> }
>>>>>> set{
>>>>>> gExcel = value;
>>>>>> }
>>>>>> }
>>>>>> public string Path(){
>>>>>> return Excel.ThisWorkb ook.Path;
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> I get a compile error saying that - 'object' does not contain a
>>>>>> definition for 'ThisWorkbook'
>>>>>>
>>>>>> How can I get this to work?
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> Alan
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

[Alvin Bruney - ASP.NET MVP]

Re: CSharp VB Excel COM Differences

On a side note, you can optimize your loop heavy code to take advantage of
the excel internally supported methods.
[color=blue]
> double total = 0;
> for (int i = 1; i <= 5; i++)
> {
> total += (double)GetProp erty(oRange, "Cells(" + i.ToString() +",
> 1").Value");
> }[/color]

can be replaced with
Range r = rangeInQuestion .Formula = "=Sum(1,5)"

FYI

--
Regards,
Alvin Bruney [MVP ASP.NET]

[Shameless Author plug]
The Microsoft Office Web Components Black Book with .NET
Now Available @ www.lulu.com/owc
Forth-coming VSTO.NET - Wrox/Wiley 2006
-------------------------------------------------------



"Alan Roberts" <alan@statistix l.co.uk> wrote in message
news:OwvHEFsEGH A.140@TK2MSFTNG P12.phx.gbl...[color=blue]
> Thanks Nicholas. I guess I am still having dificulties with the Release
> idea....
> I have come up with the following routine in C#
>
>
> private static object GetProperty(obj ect obj, string sProperty)
> {
> string[] Properties = sProperty.Split (new char[] {'.'});
> object oProp;
> oProp = obj;
> for (int i = 0; i <= Properties.GetU pperBound(0); i++)
> {
> if (Properties[i].Contains("("))
> oProp = oProp.GetType() .InvokeMember(P roperties[i].Substring(0,
> Properties[i].IndexOf('(')),
> BindingFlags.Ge tProperty, null, oProp,
> Properties[i].Substring(Prop erties[i].IndexOf('(')
> + 1, Properties[i].IndexOf(')') - (Properties[i].IndexOf('(') +
> 1)).Split(new char[] { ','
> }));
> else
> oProp = oProp.GetType() .InvokeMember(P roperties[i],
> BindingFlags.Ge tProperty, null,
> oProp, null);
> }
>
> return oProp;
> }
>
>
> basically it simplifies my code as I once I have a link to the Excel[/color]
object[color=blue]
> I can access properties using code along the lines of
> GetProperty(oEx cel, "ActiveSheet.Ce lls(1,1).Value" );
> rather than having all of the step by step code I presented previousle.
>
> If I use this function in a routine to calculate the total of a range of
> cells eg
>
>
> double total = 0;
> for (int i = 1; i <= 5; i++)
> {
> total += (double)GetProp erty(oRange, "Cells(" + i.ToString() +",
> 1").Value");
> }
>
>
> What objects do I have to release both in the for loop code above and in[/color]
the[color=blue]
> GetProperty function that it calls?
>
> Thanks for your help with this
>
> Alan
>
>
>
> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om> wrote[/color]
in[color=blue]
> message news:eaTawxpCGH A.2036@TK2MSFTN GP14.phx.gbl...[color=green]
> > Alan,
> >
> > The problem still exists in VB. In VB, the RCW for all of the[/color][/color]
objects[color=blue][color=green]
> > I list out still are out there, and you don't release them.
> >
> > The only thing that VB makes easier is having to actually make the
> > calls, it will make it easy to perfrom the reflection for you, but not[/color][/color]
the[color=blue][color=green]
> > actuall calls to ReleaseComObjec t.
> >
> >
> > --
> > - Nicholas Paldino [.NET/C# MVP]
> > - mvp@spam.guard. caspershouse.co m
> >
> > "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> > news:uQob93ICGH A.216@TK2MSFTNG P15.phx.gbl...[color=darkred]
> >> Blimey! Thanks a lot Nicholas. I guess I will stick with VB for now.
> >> On the whole I find C# more elegant but VB seems better suited to this
> >> particular application.
> >>
> >> Thanks
> >>
> >> Alan
> >>
> >> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om>[/color][/color][/color]
wrote[color=blue][color=green][color=darkred]
> >> in message news:edpv$VFCGH A.916@TK2MSFTNG P10.phx.gbl...
> >>> Alan,
> >>>
> >>> Yes, it's something like that. You could cut down on some of the
> >>> reflection calls, but not by much.
> >>>
> >>> Also, you need to call ReleaseComObjec t for each object you expose.
> >>> For example, in your Sum method, you need to release the result[/color][/color][/color]
returned[color=blue][color=green][color=darkred]
> >>> from:
> >>>
> >>> Excel.Range - Returns a collection of ranges
> >>> Excel.Range(ran ge) - Returns the individual range.
> >>> Excel.Range(ran ge).Rows - Returns the collection of ranges.
> >>> Excel.Range(ran ge).Columns - Returns the collection of columns
> >>> Excel.Range(ran ge).Cells - Returns the collection of cells.
> >>> Excel.Range(ran ge).Cells(i, j) - Returns the range representing the
> >>> individual cell.
> >>>
> >>> All of those need to have their references released properly.
> >>>
> >>> Hope this helps.
> >>>
> >>>
> >>> --
> >>> - Nicholas Paldino [.NET/C# MVP]
> >>> - mvp@spam.guard. caspershouse.co m
> >>>
> >>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> >>> news:u50iW68BGH A.412@TK2MSFTNG P15.phx.gbl...
> >>>> Hi Nicholas, thanks for the thorough reply! Does this mean that the
> >>>> following simple VB code to calculate the sum of the values specified
> >>>> in an Excel Range object
> >>>>
> >>>> Public Function Sum(ByVal range As String) As Double
> >>>> Dim i, j As Integer
> >>>> Dim total As Double
> >>>> For i = 1 To Excel.Range(ran ge).Rows.Count
> >>>> For j = 1 To Excel.Range(ran ge).Columns.Cou nt
> >>>> total = total +[/color][/color][/color]
Convert.ToDoubl e(Excel.Range(r ange).cells(i,[color=blue][color=green][color=darkred]
> >>>> j).value)
> >>>> Next j
> >>>> Next i
> >>>> Return total
> >>>> End Function
> >>>>
> >>>>
> >>>> must become something like this in C#???
> >>>>
> >>>>
> >>>> public double Sum(string range)
> >>>> {
> >>>> object oRange, oRows, oCols, oRowCount, oColCount, oCell, oValue;
> >>>> object[] Parameters;
> >>>> double total= 0;
> >>>> Parameters = new Object[1];
> >>>> Parameters[0] = range;
> >>>> oRange = Excel.GetType() .InvokeMember(" Range",
> >>>> BindingFlags.Ge tProperty, null, Excel, Parameters);
> >>>> oRows = oRange.GetType( ).InvokeMember( "Rows",
> >>>> BindingFlags.Ge tProperty, null, oRange, null);
> >>>> oRowCount = oRows.GetType() .InvokeMember(" Count",
> >>>> BindingFlags.Ge tProperty, null, oRows, null);
> >>>> oCols = oRange.GetType( ).InvokeMember( "Columns",
> >>>> BindingFlags.Ge tProperty, null, oRange, null);
> >>>> oColCount = oCols.GetType() .InvokeMember(" Count",
> >>>> BindingFlags.Ge tProperty, null, oCols, null);
> >>>> for (int i = 1; i <= (int)oColCount; i++)
> >>>> {
> >>>> for (int j = 1; j <= (int)oRowCount; j++)
> >>>> {
> >>>> Parameters = new Object[2];
> >>>> Parameters[0] = j;
> >>>> Parameters[1] = i;
> >>>> oValue = new Object();
> >>>> oCell = new Object();
> >>>> oCell = oRange.GetType( ).InvokeMember( "Cells",
> >>>> BindingFlags.Ge tProperty, null, oRange, Parameters);
> >>>> oValue = oCell.GetType() .InvokeMember(" Value",
> >>>> BindingFlags.Ge tProperty, null, oCell, null);
> >>>> total += (double)oValue;
> >>>> }
> >>>> }
> >>>> return total;
> >>>> }
> >>>>
> >>>>
> >>>> Or is there a better way?
> >>>>
> >>>> Thanks
> >>>>
> >>>> Alan
> >>>>
> >>>>
> >>>>
> >>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard .caspershouse.c om>
> >>>> wrote in message news:OSx564zBGH A.2920@tk2msftn gp13.phx.gbl...
> >>>>> Alan,
> >>>>>
> >>>>> The reason this works in VB is that the VB compiler will[/color][/color][/color]
translate[color=blue][color=green][color=darkred]
> >>>>> property and method calls on variables of type object to be[/color][/color][/color]
reflection[color=blue][color=green][color=darkred]
> >>>>> calls, which cause your code to work.
> >>>>>
> >>>>> Unfortunately, C# doesn't support this functionality. You will
> >>>>> have to use reflection to get the member names and then invoke them
> >>>>> like that.
> >>>>>
> >>>>> OR, you could set a reference to the interop assemblies for[/color][/color][/color]
Excel,[color=blue][color=green][color=darkred]
> >>>>> and cast the object passed into your method into one of those[/color][/color][/color]
classes[color=blue][color=green][color=darkred]
> >>>>> in the interop assembly. This would prevent you from having to do[/color][/color][/color]
any[color=blue][color=green][color=darkred]
> >>>>> late binding.
> >>>>>
> >>>>> Also, you should be careful of the operations you are performing.
> >>>>> When you call methods on any object in Excel, you are creating a
> >>>>> runtime callable wrapper which should be disposed of if you aren't
> >>>>> using it anymore. In the case of your Path property, you should
> >>>>> assign the result of ThisWorkbook to a variable, then pass that to[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> >>>>> static ReleaseComObjec t method on the Marshal class.
> >>>>>
> >>>>> Hope this helps.
> >>>>>
> >>>>>
> >>>>> --
> >>>>> - Nicholas Paldino [.NET/C# MVP]
> >>>>> - mvp@spam.guard. caspershouse.co m
> >>>>>
> >>>>> "Alan Roberts" <alan@statistix l.co.uk> wrote in message
> >>>>> news:%23FJb3JuB GHA.2704@TK2MSF TNGP15.phx.gbl. ..
> >>>>>> Can someone please explain the following for me...
> >>>>>>
> >>>>>> I am trying to link to a .NET DLL from Excel. Excel needs to pass[/color][/color][/color]
a[color=blue][color=green][color=darkred]
> >>>>>> reference to itself to the DLL and then the DLL needs to perform[/color][/color][/color]
some[color=blue][color=green][color=darkred]
> >>>>>> work on the running instance of Excel via that reference. As an
> >>>>>> example, a VB DLL to return the path to the current active workbook
> >>>>>> contains the following (in addition to the COM GUIDS automatically
> >>>>>> added to a new COMClass)...
> >>>>>>
> >>>>>> Public Class Class1
> >>>>>> Public Sub New()
> >>>>>> MyBase.New()
> >>>>>> End Sub
> >>>>>> Private gExcel As Object
> >>>>>> Public Property Excel() As Object
> >>>>>> Set(ByVal value As Object)
> >>>>>> gExcel = value
> >>>>>> End Set
> >>>>>> Get
> >>>>>> Excel = gExcel
> >>>>>> End Get
> >>>>>> End Property
> >>>>>> Public Function Path() As String
> >>>>>> Return Excel.ThisWorkb ook.Path
> >>>>>> End Function
> >>>>>> End Class
> >>>>>>
> >>>>>> After adding a refernece to the DLL, a macro in Excel could call[/color][/color][/color]
this[color=blue][color=green][color=darkred]
> >>>>>> as follows
> >>>>>>
> >>>>>> Sub VBTest()
> >>>>>> Dim VBTest As New VBExcelTest.Cla ss1
> >>>>>> Set VBTest.Excel = Application
> >>>>>> Debug.Print VBTest.Path
> >>>>>> End Sub
> >>>>>>
> >>>>>> This all work fine
> >>>>>>
> >>>>>> How can I do the same thing using C#? If I try to create a DLL[/color][/color][/color]
with[color=blue][color=green][color=darkred]
> >>>>>> equivalent(?) code eg
> >>>>>>
> >>>>>> public class Class1
> >>>>>> {
> >>>>>> public Class1(){
> >>>>>> }
> >>>>>> private object gExcel;
> >>>>>> public object Excel{
> >>>>>> get{
> >>>>>> return gExcel;
> >>>>>> }
> >>>>>> set{
> >>>>>> gExcel = value;
> >>>>>> }
> >>>>>> }
> >>>>>> public string Path(){
> >>>>>> return Excel.ThisWorkb ook.Path;
> >>>>>> }
> >>>>>> }
> >>>>>>
> >>>>>> I get a compile error saying that - 'object' does not contain a
> >>>>>> definition for 'ThisWorkbook'
> >>>>>>
> >>>>>> How can I get this to work?
> >>>>>>
> >>>>>> Thanks
> >>>>>>
> >>>>>> Alan
> >>>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>[/color]
> >
> >[/color]
>
>[/color]