Professional IronPython

 Testing the extension using IronPython
# Add a reference to the CLR
import clr
# Obtain access to the extension.
clr.AddReferenceToFile(‘Calcs.DLL’)
import Calcs
# Create an instance of the class and fill it with data.
Value1 = Calcs.Calcs(10)
# Print the original value, then decrement and increment it.
print ‘Original Value1 Content: ‘, Value1 
print ‘Value1 + 1: ‘, Value1.Inc() 
print ‘Value1 - 1: ‘, Value1.Dec()
# Create a second value and display it.
Value2 = Calcs.Calcs(5) 
print ‘\nOriginal Value2 Content: ‘, Value2
# Use the two values together in different ways.
print ‘\nValue1 + Value2 = ‘, Value1 + Value2
continues
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CHAPTER 16
ExtEnding ironPython Using C#
print ‘Value1 - Value2 = ‘, Value1 - Value2
print ‘Value1 * Value2 = ‘, Value1 * Value2
print ‘Value1 / Value2 = ‘, Value1 / Value2
# Pause after the debug session.
raw_input(‘\nPress any key to continue...’)
The example begins by importing support for the Common Language Runtime (CLR). It then uses the 
AddReferenceToFile()
method to reference the 
Calcs.DLL
file and imports the code into IronPython. 
These steps are similar to those that you used to test the DLL initially.
The next step is to create an instance of the 
Calcs
class, 
Value1
. The code references 
Calcs
twice — 
once for the namespace and a second time for the class itself. The next few code steps display the 
value of 
Value1
and show how to use the 
Inc()
and 
Dec()
methods. If you set 
Value1
equal to 
the output of 
Inc()
or 
Dec()
, it truly would increment or decrement the value of 
Value1
. Because 
IronPython doesn’t support the 
++
operator, however, you can’t use the 
++
operator in your exten-
sion. On the other hand, you could implement the 
+=
and 
-=
operators.
You can’t really test binary operators without a second variable, so the code creates a second 
instance of 
Calcs
, 
Value2
. The example then shows how the 
+
, 
-
, 
*
, and 
/
operators work. 
Figure 16-7 shows the output from this example.