Re: Shared functions vs Non-Shared Functions

"Karl Seguin" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net>
wrote in message news:O%238$KwiYFHA.4032@xxxxxxxxxxxxxxxxxxxxxxx
> You would create an instance class with instance members if you wanted to
> create an Email object, set it's properties and have a Send() method, ala:
>
> dim email as new Email("some subject")
> email.Body = "xxx"
> email.Send()
>
>
> you would use a shared member if you wanted to pass everything in as
> parameters
>
> EmailHelp.Send("some subject", "xxx")
>
> I personally prefer the syntax of the 2nd example...but if you wanted to
> keep a bunch of different emails, say you wanted to cache them or move
> them around between your layers, it'd be necessary to have distinct
> instances.

I prefer the 2nd example also.

But when you talk about caching or moving them, are you saying that you want
an instance so you could do something like:

sub somefunction (myEmail as Email)
....
myEmail.somemethod()

end sub

Then using your 1st example:

dim email as new Email("some subject")
email.Body = "xxx"
email.Send()
....
somefunction(email) ' calling the above function


BTW, I took my email function and tried to compile it using:

C:\Inetpub\wwwroot\staffingworkshop>vbc /t:library email.vb
/r:system.web.dll /r:system.data.dll /r:system.dll
/r:Microsoft.VisualBasic.dll

and I get the following errors:

C:\Inetpub\wwwroot\staffingworkshop\email.vb(49) : error BC30469: Reference
to a non-shared member requires an object reference.

I am getting this for request.path and for MapPath.

My file looks like:
**********************************************************************************
Imports System
Imports System.Web
Imports System.IO
Imports System.Web.UI
Imports System.Web.SessionState
Imports System.Web.Mail
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.HttpCookie
Imports System.Web.HttpCookieCollection
Imports System.Web.HttpResponse
Imports System.Web.HttpRequest
Imports System.Web.HttpApplication
Imports System.Web.HttpApplicationState
Imports Microsoft.VisualBasic

NameSpace MyFunctions

Public Class Email

Public Shared sub sendEmail ( )
dim webMasterEmail As String
dim emailSubject As String
Dim mailServer As String
Dim contactEmail As String
Dim screenTestSubject As String

Dim emailReader As SqlDataReader

Dim ConnectionString as String
=System.Configuration.ConfigurationSettings.AppSettings("MM_CONNECTION_STRING_ftsolutions")
Dim objConn as New SqlConnection (ConnectionString)
Dim CommandText as String = "Select
MailServer,WebMasterEmail,ContactEmail,ScreenTestSubject from emailResponse
where ClientID = '1234'"
Dim objCmd as New SqlCommand(CommandText,objConn)

objConn.Open()

emailReader = objCmd.ExecuteReader

if emailReader.Read then
mailServer = emailReader("MailServer")
webMasterEmail = emailReader("WebMasterEmail")
contactEmail = emailReader("ContactEmail")
screenTestSubject = emailReader("ScreenTestSubject")
end If

objConn.close()

dim URLPath As String = _
Left(request.path, InStrRev(request.path, "/") - 1)

Dim objStreamReader as StreamReader
Dim strInput As String
Dim strBuffer As String

If File.exists(MapPath("..\..\automail\new_account_automail.htm")) then
objStreamReader =
File.OpenText(MapPath("..\..\automail\new_account_automail.htm"))
strInput = objStreamReader.ReadLine()
while strInput <> nothing
strBuffer = strBuffer & strInput
strInput = objStreamReader.ReadLine()
end while
objStreamReader.Close
end if

Dim Message As New MailMessage()
message.To = contactEmail
message.From = webMasterEmail
message.Subject = screenTestSubject
message.Body = "This is line 1<br><br>"
message.Body = message.Body & "This is line 2<br><br>"
strInput = strBuffer.replace("#MESSAGE#",message.Body)
strInput = strInput.replace("#MAILTITLE#","Screen Test Confirmation")
message.Body = strInput
message.BodyFormat = MailFormat.Html
SmtpMail.SmtpServer = mailServer
smtpMail.Send(message)
end sub

End Class

End Namespace
************************************************************************************

This happens whether emailSend is Shared or not.

Thanks,

Tom

>
> Trust your gut feeling.
>
> Karl
>
> --
> MY ASP.Net tutorials
> http://www.openmymind.net/ - New and Improved (yes, the popup is
> annoying)
> http://www.openmymind.net/faq.aspx - unofficial newsgroup FAQ (more to
> come!)
> "tshad" <tscheiderich@xxxxxxxxxxxxxxx> wrote in message
> news:%23EYViOiYFHA.1404@xxxxxxxxxxxxxxxxxxxxxxx
>> "Karl Seguin" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net>
>> wrote in message news:e5dfeFiYFHA.3364@xxxxxxxxxxxxxxxxxxxxxxx
>>> Tom:
>>> Is the function manipulating instance data? Looking at your functions,
>>> they look like they need to be shared.
>>>
>>> Think of it this way.
>>>
>>> You have a class called Car, which has a property named AirbagDeployed
>>> as boolean
>>>
>>> if you have a function named DeployAirbag() it would need to be an
>>> instance (non-shared) method. Why? Because you would have create a new
>>> car instance and would want to deploy that particular car's airbag. in
>>> other words, instnace methods behave against a particular instance.
>>> Your BitHandling class looks like a helper function for dealing with bit
>>> information. You wouldn't create separate instance of them as you don't
>>> need to represent different bithandling (as you would differnent
>>> cars)...ergo your function don't behave against instances.
>>>
>>> A case where you might have instances is if your BitHandling was
>>> culture-specific. In which case you might have different bithandling
>>> instances per culture. In this case you'd need to create a new
>>> BitHandling class (specifying the culture) and then your functions would
>>> behave against that particular instance. (As an aside, an alternative
>>> would be to pass the culture information to each shared function so you
>>> wouldn't need to create culture-specific instances which works fine for
>>> a single parameter, but becomes messy when you're talking about more..)
>>
>> That's what gets confusing. Trying to figure out the instances bit (no
>> pun intended) and if it is needed. Here is the other function that I am
>> creating to put in my MyFunctions Namespace. I would give is a class of
>> email, I suppose.
>>
>> This is just my prototype email program that I am putting together to
>> make a more generalized function from.
>>
>> It, in essence:
>> gets the connection to Sql
>> gets the email record to get the subject and from/to addresses
>> reads a text file to put into the body of the message
>> adds a few things to the email
>> sends the email
>>
>> I would probably change the function to something like:
>>
>> public shared sendEmail(filename as string, subject as string)
>>
>> ***************************************************************************************
>> sub sendEmail ( )
>> dim webMasterEmail As String
>> dim emailSubject As String
>> Dim mailServer As String
>> Dim contactEmail As String
>> Dim screenTestSubject As String
>>
>> Dim emailReader As SqlDataReader
>>
>> Dim ConnectionString as String
>> =System.Configuration.ConfigurationSettings.AppSettings("MM_CONNECTION_STRING_solutions")
>> Dim objConn as New SqlConnection (ConnectionString)
>> Dim CommandText as String = "Select
>> MailServer,WebMasterEmail,ContactEmail,ScreenTestSubject from
>> emailResponse where ClientID = '1234'"
>> Dim objCmd as New SqlCommand(CommandText,objConn)
>>
>> objConn.Open()
>>
>> emailReader = objCmd.ExecuteReader
>>
>> if emailReader.Read then
>> mailServer = emailReader("MailServer")
>> webMasterEmail = emailReader("WebMasterEmail")
>> contactEmail = emailReader("ContactEmail")
>> screenTestSubject = emailReader("ScreenTestSubject")
>> end If
>>
>> objConn.close()
>>
>> dim URLPath As String = _
>> Left(request.path, InStrRev(request.path, "/") - 1)
>>
>> Dim objStreamReader as StreamReader
>> Dim strInput As String
>> Dim strBuffer As String
>>
>> If File.exists(MapPath("\new_account_automail.htm")) then
>> objStreamReader = File.OpenText(MapPath("\new_account_automail.htm"))
>> strInput = objStreamReader.ReadLine()
>> while strInput <> nothing
>> strBuffer = strBuffer & strInput
>> strInput = objStreamReader.ReadLine()
>> end while
>> objStreamReader.Close
>> end if
>>
>> Dim Message As New MailMessage()
>> message.To = contactEmail
>> message.From = webMasterEmail
>> message.Subject = screenTestSubject
>> message.Body = "This is line 1<br><br>"
>> message.Body = message.Body & "This is line 2<br><br>"
>> strInput = strBuffer.replace("#MESSAGE#",message.Body)
>> strInput = strInput.replace("#MAILTITLE#","Screen Test Confirmation")
>> message.Body = strInput
>> message.BodyFormat = MailFormat.Html
>> SmtpMail.SmtpServer = mailServer
>> smtpMail.Send(message)
>> end sub
>> *****************************************************************************
>>
>> Would this work as a shared function, or would I need to make this an
>> instance?
>>
>> Thanks,
>>
>> Tom
>>>
>>> Karl
>>>
>>>
>>>
>>> --
>>> MY ASP.Net tutorials
>>> http://www.openmymind.net/ - New and Improved (yes, the popup is
>>> annoying)
>>> http://www.openmymind.net/faq.aspx - unofficial newsgroup FAQ (more to
>>> come!)
>>> "tshad" <tscheiderich@xxxxxxxxxxxxxxx> wrote in message
>>> news:uBJT31hYFHA.2756@xxxxxxxxxxxxxxxxxxxxxxx
>>>>I am setting up some of my functions in a class called MyFunctions.
>>>>
>>>> I am not clear as to the best time to set a function as Shared and when
>>>> not to. For example, I have the following bit manipulation routines in
>>>> my Class:
>>>>
>>>> *******************************************************************************
>>>> imports System
>>>>
>>>> NameSpace MyFunctions
>>>>
>>>> Public Class BitHandling
>>>>
>>>> '*----------------------------------------------------------*
>>>> '* Name : BitSet *
>>>> '*----------------------------------------------------------*
>>>> '* Purpose : Sets a given Bit in Number *
>>>> '*----------------------------------------------------------*
>>>> Public Shared Function BitSet(Number As Integer, _
>>>> ByVal Bit As Integer) As Long
>>>> If Bit = 31 Then
>>>> Number = &H80000000 Or Number
>>>> Else
>>>> Number = (2 ^ Bit) Or Number
>>>> End If
>>>> BitSet = Number
>>>> End Function
>>>>
>>>> '*----------------------------------------------------------*
>>>> '* Name : BitClear *
>>>> '*----------------------------------------------------------*
>>>> '* Purpose : Clears a given Bit in Number *
>>>> '*----------------------------------------------------------*
>>>> Public Shared Function BitClear(Number As Integer, _
>>>> ByVal Bit As Integer) As Long
>>>> If Bit = 31 Then
>>>> Number = &H7FFFFFFF And Number
>>>> Else
>>>> Number = ((2 ^ Bit) Xor &HFFFFFFFF) And Number
>>>> End If
>>>>
>>>> BitClear = Number
>>>> End Function
>>>>
>>>> '*----------------------------------------------------------*
>>>> '* Name : BitIsSet *
>>>> '*----------------------------------------------------------*
>>>> '* Purpose : Test if bit 0 to bit 31 is set *
>>>> '*----------------------------------------------------------*
>>>> Public Shared Function BitIsSet(ByVal Number As Integer, _
>>>> ByVal Bit As Integer) As Boolean
>>>> BitIsSet = False
>>>>
>>>> If Bit = 31 Then
>>>> If Number And &H80000000 Then BitIsSet = True
>>>> Else
>>>> If Number And (2 ^ Bit) Then BitIsSet = True
>>>> End If
>>>> End Function
>>>>
>>>> End Class
>>>>
>>>> End Namespace
>>>>
>>>> ********************************************************************************
>>>>
>>>> Now I have these set up as shared so I don't have to create an instance
>>>> of the class:
>>>>
>>>> temp = BitHandling.BitSet(temp,3)
>>>>
>>>> vs.
>>>>
>>>> dim MyBits as new BitHandling
>>>> temp = MyBits.BitSet(temp,3)
>>>>
>>>> I am also setting up my function to send out various emails which
>>>> entails reading an Sql Record and reading a text file from disk, as
>>>> well as sending the email:
>>>>
>>>> SmtpMail.SmtpServer = mailServer
>>>> smtpMail.Send(message)
>>>>
>>>> What would tell me that I need to make this a non-shared function vs a
>>>> shared one?
>>>>
>>>> Thanks,
>>>>
>>>> Tom
>>>>
>>>
>>>
>>
>>
>
>


.

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