Running python functions sequentially if each function doesn't throw any error

Question

I would like to write a python code that run several functions sequentially. Actually, start from first function and check if it doesn't throw any error, then start running second function and so on. I used following strategy, but it didn't stop when first function throws error and keep running other function:

    try:
        firstFunc()
    except:
        raise ExceptionFirst('job failed!')
    else:
        try:
            secondFunc()
        except:
            raise ExceptionSecond('second function failed!')

------------------------------ ADD-ON-------------------------------------------

All functions defined in a separate way and don't have connection with each other. The structure of each function is like following (e.g., first fucntion):

p = subprocess.Popen("abaqus script=py.py", shell=True)
p.communicate() #now wait
if p.returncode == 0:
    print("job is successfully done!")

I changed my function as follows and it worked successfully:

p = subprocess.check_call("abaqus script=py.py", shell=True)
if p == 0:
    print("job is successfully done!")

But, I stuck with the same problem for one of my functions which has following structure:

p = subprocess.check_call("java -jar javaCode.jar XMLfile.xml", shell=True)
if p == 0:
    print("job is successfully done!")

It throws an error, but the python print out "job is successfully done!" for that and keeps running other functions!!

---------------------------------------- Full Code ------------------------------------------------

import subprocess
import sys, os

def abq_script():
    p = subprocess.check_call("abaqus script=py.py", shell=True)
    if p == 0:
        print("job is successfully done!\n")

def abq_java():
    p = subprocess.check_call("java -jar FisrtJavaCode.jar", shell=True)
    if p == 0:
        print("job is successfully done!\n")

def java_job():
    p = subprocess.check_call("java -jar secondJavaCode.jar XMLfile.xml", shell=True)
    if p == 0:
        print("job is successfully done!\n")

def abq_python_java():  
    funcs = [abq_script, abq_java, java_job]
    exc = Exception('job failed!')
    for func in funcs:
        try:
            func()
        except Exception as e:
            print(str(e))
            break

If the first or second function shows an error, the exception throws an exception and program stops from running. But, if last function (java_job) shows an error, program doesn't throw any exception and keeps running.

Answer 1

Put your functions into a list and iterate through them, calling each.

funcs = [firstFunc, secondFunc, ...]
for func in funcs:
    try:
        func()
    except ValueError: # Or whatever specific exception you want to handle...
        # Handle it...
        break

(See here for discussion of why it's far better to catch the specific exception you're trying to handle.)

Edit:

If each function has a specific set of exceptions that you'd like to catch, but it differs for the functions, you could put them into the list with the functions.

funcs = [
    (firstFunc, (ValueError, TypeError)),
    (secondFunc, (ZeroDivisionError, NameError)),
    # More function and their exceptions here...
]
for func, exceptions_to_catch in funcs:
    try:
        func()
    except exceptions_to_catch: 
        # Handle it...
        break

More edit:

I'd structure this differently - the only thing that differs between jobs is the command to run. You could do this with something like:

commands = [
    "abaqus script=py.py",
    "java -jar FisrtJavaCode.jar",
    "java -jar javaCode.jar XMLfile.xml",
]
for command in commands:
    subprocess.check_call(command, shell=True)
    print 'command {!r} successfully done!'.format(command)    

You don't need to catch the subprocess.CalledProcessError that might be thrown if one of the commands sets a nonzero return code - that'll stop processing the way you want.

Now it sounds like the underlying problem is that java -jar javaCode.jar XMLfile.xml doesn't set the return code correctly when it fails.

Answer 2

Why are you trying to try/except if you're only throwing another exception? Let the original exception bubble up if you're trying to stop execution thereafter.

firstFunc()
secondFunc()
thirdFunc()
we_all_about_the_funk()