Embedded python in InterSystems IRIS Part-2

In the previous article. Practices of class members and their execution within embedded Python. We will now turn our attention to the process of switching namespaces, accessing global variables , traversing and routine executions within embedded Python.

Before proceeding to the other functions. let us briefly review the execute function within the iris package. This function is exceptionally beneficial for executing the arbitrary ObjectScript functions and class invocation.

Let us begin!

4. Switch Namespaces

Switching namespaces during execution is often necessary. However, unlike in IRIS, direct switching of namespaces within embedded Python is not feasible. Therefore, it is essential to utilize existing class definitions or to create a wrapper method to facilitate the switching of namespaces.  

ClassMethod SwitchNM() [ Language = python ]
{
    import iris
    print(iris.cls('%SYSTEM.SYS').NameSpace())
    print(iris.system.Process.SetNamespace("USER"))
    try:
        iris.cls('User.EmbeddedPython').pyGetTemplateString()
    except RuntimeError as e:
        print("Wrong NameSpace",e)
}

5. Global

To utilize the capabilities of global for data traversal or to retrieve information from legacy global systems directly, rather than through SQL or objects within embedded Python, one can access it directly by employing the gref function from the iris package. To set or get global values, the gref function can be utilized to establish a reference to the global variable and directly assign values within Python.

5.1 Set global values

ClassMethod SetGlobal() [ Language = python ]
{
import iris
#create a global reference
g = iris.gref('^mygbl') 
g[1],g[2]='Mon','Tue'
g["95752455",1]=iris.execute('return $LFS("Ashok,55720,9639639639,test@gmail.com",",")')
g["85752400",1]=iris.execute('return $LB("Test","9517539635","t@gmail.com")')
g["test","c1"]=iris.execute('return ##Class(MyLearn.EmbeddedPython).executeAndGetResult()') # method wil return some listbuild values
# declare values by using set function
g.set([3],'Wed')
g.set([3,1,1],'Test multilevel')
}

5.2 get global values
Fetch the global values from python directly by using the subscripts or get method.

ClassMethod GetGlobal() [ Language = python ]
{
    import iris
    #gets a global reference
    g = iris.gref('^mybgl') 
    # get values
    print(g[3,1,1])
    print(g.get([2,1]))
    print(g["95752455",1])
}

5.3 Traversal 

order - Traversing the global is essential for collecting multiple level of data's from global. This embedded Python  order functions similarly to the $Order command, utilizing the order function from the iris.gref. Initially, it is necessary to establish a reference to the global entity that requires traversal.

Single subscript level traversal

ClassMethod DollarOrder() [ Language = python ]
{
    import iris
    g = iris.gref('^MyLearn.EmbeddedPythonD') # I use my persistent class global
    key = ''
    while True:
        key = g.order([key])
        if key == None:
            break
        print(f'{key} {g.get([key])}')
}

Multi subscript level traversal

ClassMethod DollarOrderMultiLevel() [ Language = python ]
{
 import iris
 g = iris.gref('^mygbl')
 key1= ''
 while True:
 	key1 = g.order([key1])
 	if key1== None:
 		break
 	key2 = ''
 	while True:
 		key2 = g.order([key1,key2])
 		if key2 == None:
 			break
 		value = g.get([key1,key2])
 		print(key1,key2,value)
}

ClassMethod DollarQuery() [ Language = python ]
{
 	import iris
 	g = iris.gref('^mygbl')
 	key = g.query()#this will return tuples of all the subscripts
 	for x in key:
 		print(x) # output (['3', '1', '1'], 'Test multilevel')
}

ClassMethod DollarData() [ Language = python ]
{
    import iris
    g = iris.gref('^mygbl')
    key1= ''
    print(g.data([1]))
}

ClassMethod RunRoutines() [ Language = python ]
{
    import iris
    iris.routine('^myirispython')
    iris.routine('add^myirispython',1,2) # same as write $$add^myirispython(1,2)
}