1. Geography 465 Managing Custom Python Script Tools

2. Considerations for Creating Script Tools
End User
Purpose of the script tools
Toolbox organization
Documentation
Code structure
Reusable components, error handling, more
How to implement
Where to store, how to distribute, future tools, etc.
Mainteance issues

3. Organizing your script tools
Create the script tools (associate each with a .py script)
Group common tools into toolsets
Group toolsets into toolbox

4. Understanding program flow
Top-level file (.py file)
Module that you can run
Controls the flow
Can import other modules (.py files)
Module_1
Module_A
Module_B
Module_C
Module_D
Top-level file
Imported modules

5. Example: Spatial Statistics Toolbox
DirectionalDistribution.py
Top-level file
CentralFeature.py
sys os
locale
HelperFunctions
sys os
locale
HelperFunctions
sys os
locale
math
random
Other spatial statistics tools
import HelperFunctions
HelperFunctions.py
import sys, math, os, locale, random, tempfile,
arcgisscripting

6. Ways of importing More than one way to import
import; entire module; requires module prefix
import math
math.sin (x)
from…import; specific names from module
from math import sin, cos,
sin(x)
from…import *
from math import *
tan (x)
Affects: readability, name collision, ability to reload

7. Code order Writing custom functions Functions: Put functions at top
Put top-level code at bottom so functions are recognized
Functions:
def…
top-level code…

8. Controlling access to functions and variables
Each module has a built in _ _name_ _atttribute
Module can test its own _ _name_ _
Top-level file module:
_ _name_ _ is equal to _ _main_ _
Imported module:
_ _name_ _ is equal to <modulename>
_ _main_ _ prevents access when module is imported for
def statements
Variables

9. Code example: Control access
MyTool.py
import Example
fmc = Example.find_most_central() …
ac = Example.areaCalc()
Example.py
import arcgisscripting
gp = arcgisscripting.create()
def get_imputs (arguments): # access unrestricted
df find_most_central(): # in calling module
if _ _name_ _ = “_ _main_ _”: # access restricted
def areaCalc(…) # in calling module