Classes in Namespaces

Description

In Implementing an Xbasic Class we defined a class:

define class global StoredProc
dim protected m_Connection as SQL::Connection
dim public read protected write SPKeyword as C = ""
...

That class might conflict with someone else's StoredProc class sometime in the future. To avoid naming collisions, we can put the class into a namespace. For example, this class can become:

define class Demo::StoredProc
dim protected m_Connection as SQL::Connection
dim public read protected write SPKeyword as C = ""
...

We have removed the global keyword, as scope is not meaningful for namespaces in Alpha Five.

Save the revised class as Demo.StoredProc. Note that we did the class definition with two colons between the namespace and the class name, but saved the definition in a file with a period between the namespace and the class name. This may be confusing, but it is necessary as the Windows file system is not happy when it sees colons in file names except when they delimit volumes, for example C:\directory\filename.ext.

You can now use the class by DIMming it:

dim sp as Demo::StoredProc

As an additional benefit, once the class has been loaded, you will see the class in the namespace in a dropdown as soon as you type Demo:::

To ensure that your namespaces do not collide with other people's namespaces, you can prefix them with your company name or another unique identifier. So, for example, you could define this class:

define class myCompany.myNamespace::mySampleClass
 dim sampleVar1 as c = ""
function sampleMethod1 as v()
    ui_msg_box("Hello, World!",self.sampleVar1)
    end function
end class

You would save this as myCompany.myNamespace.mySampleClass. Note that the different parts of the namespace name are separated by single periods, not by two colons. In an interactive window you could then DIM and use the class:

dim sample as myCompany.myNamespace::mySampleClass
?sample.sampleVar1
= ""

See Also