User manual

def displayStatus(msg1, msg2):
print msg1 + msg2
…but in your SNAPpy scripts you have RPC calls like…
rpc(PORTAL_ADDR, "displayStatus", 1, 2, 3) # <- too many parameters provided
…or…
rpc(PORTAL_ADDR, "displayStatus", 1) # <- too few parameters provided
…then you are going to see no output at all in Portal. Because the “signatures” do not match, Portal does not
invoke the
displayStatus() funcon at all.
You can change the calling SNAPpy script(s), or you can change the Portal script, but they must match.
Funcons can return values
def adder(a, b):
return a + b
print adder(1, 2) # would print out "3"
Funcons can do nothing
def placeHolder(a, b):
pass
Funcons cannot be empty
def placeHolder(a, b):
# ERROR! - you have to at least put a "pass" statement here
# It is not sufficient to just have comments
This is also true for any code block, as might be found in a while loop or a condional branch. Each code block
must contain at least a pass statement.
Variables at the top of your script (outside the scope of a funcon definion) are global.
x = 99 # this is a global variable
def sayHello():
print "x=", x
Variables within funcons are usually local…
x = 99 # this is a global variable
def showNumber():
x = 123 # this is a separate local variable
print x # prints 123
…unless you explicitly say you mean the global one
x = 99 # this is a global variable
def showGlobal():
print x # this shows the current value of global variable x
SNAP® Network Operang System 9