Add a method to an object

Hi,

I want to add a custom method to an object, I have a function called Sanitize, this takes a string and sanitises it for SQL, currently I would call it like so:

dim str as string
str = "a 'little' form"
str = Sanitize(str)

What I would lke ot be able to do is add the function Sanitize to the string object, so to clean a string I would just type:

str.Sanitize()


How do I do this, and can yo upllease provide the correct terms for this process too?


For info, this is my Sanitize function

    Public Shared Function Sanitize(ByVal str as String) As String
        str = Replace(str, "'", "''")
        str = Replace(str, Chr(34), Chr(34) & Chr(34))
        str = HttpUtility.HtmlEncode(str)
        str = str.Replace(Environment.NewLine, "<br />")
        Sanitize = str
    End Function
LVL 4
bhermerAsked:
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Wayne Taylor (webtubbs)Connect With a Mentor Commented:
Hi bhermer,

In order to do that, you would probably want to inherit from String, which, unfortunately, cannot be done (it is sealed).

My only suggestion is to send the string to your function by reference, like this....

    Public Shared Function Sanitize(ByRef str as String) As String
        str = Replace(str, "'", "''")
        str = Replace(str, Chr(34), Chr(34) & Chr(34))
        str = HttpUtility.HtmlEncode(str)
        str = str.Replace(Environment.NewLine, "<br />")
        Sanitize = str
    End Function

....which would enable you to sanitize the string like so....

    Sanitize(str)

...instead of like before....

    str = Sanitize(str)

Regards,

Wayne
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bhermerAuthor Commented:
Hi Wayne,

Thanks for that, the ByRef makes sense. Is this true for all in bult objects? i.e you can''t inherit?
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gocemiConnect With a Mentor Commented:
Create class MyString that will inherit from String

public class MyString:String
{

 Public Shared Function Sanitize(ByVal str as String) As String
        str = Replace(str, "'", "''")
        str = Replace(str, Chr(34), Chr(34) & Chr(34))
        str = HttpUtility.HtmlEncode(str)
        str = str.Replace(Environment.NewLine, "<br />")
        Sanitize = str
    End Function

}


so INSTEAD OF creating stirng s = "sss";
you create strings ....
myString m = new MyString();

Since you inherit from string every string can be casted in to MyString Class

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Wayne Taylor (webtubbs)Commented:
Not all - String is the only one I know of for certain.
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Wayne Taylor (webtubbs)Commented:
gocemi - you can not inherit from String.
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bhermerAuthor Commented:
gocemi, thanks for that, it would work without a doubt, but would not save me any real time as I would have to declare my strings differently, Probably easier to use ByRef instead, then I can use it with any string without having to plan ahead.

I am awarding the bulk of the poitns to Wayne, as he has provided the solution I am using, but I am also awarding some to gocemi as 'technically' this did answer my question.

Thanks people.
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Wayne Taylor (webtubbs)Commented:
No disrespect, but gocemi's suggestion is plainly wrong. It is not possible to inherit from String.....

http://www.experts-exchange.com/Programming/Languages/.NET/Q_22848364.html
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gocemiCommented:
my Appologies for this,

I've never neded to do this,

Sorry man for my mistake
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bhermerAuthor Commented:
ok, sorry too, I didnt realize that that was inheriting in the direct sense, dont understand this subject particularly well.
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Wayne Taylor (webtubbs)Commented:
No problems. I just wanted to point it out to avoid any confusion.
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