How do I stop execution inside exec command in Python 3?

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I have a following code:

code = """
print("foo")

if True: 
    return

print("bar")
"""

exec(code)
print('This should still be executed')

If I run it I get:

Traceback (most recent call last):
  File "untitled.py", line 10, in <module>
    exec(code)
  File "<string>", line 5
SyntaxError: 'return' outside function

How to force exec stop without errors? Probably I should replace return with something? Also I want the interpreter work after exec call.

Here, just do something like this:

class ExecInterrupt(Exception):
    pass

def Exec(source, globals=None, locals=None):
    try:
        exec(source, globals, locals)
    except ExecInterrupt:
        pass

Exec("""
print("foo")

if True: 
    raise ExecInterrupt

print("bar")
""")
print('This should still be executed')

If your worry is readability, functions are your first line of defense.

How to stop/terminate a python script from running?, statements which is then executed unless a syntax error occurs and if it is an object code, it is simply executed. To stop code execution in Python you first need to import the sys object. After this you can then call the exit() method to stop the program running. After this you can then call the exit() method to stop the program running.

This will work, return only works from within a defined function:

code = """
print("foo")

if not True:
    print("bar")
"""
exec(code)
print('This should still be executed')

but if you want to use return, you must do something like:

code = """
def func():
    print("foo")

    if True: 
        return

    print("bar")

func()    
"""
exec(code)
print('This should still be executed')

exec() in Python, I am currently in the process of learning Python, so I thought I would start a series of mini blog posts detailing To stop code execution in Python you first need to import the sys object. circle(100, steps=3) This function resets screen. Execute shell command in Python with subprocess module. A slightly better way of running shell commands in Python is using the subprocess module. If you want to run a shell command without any options and arguments, you can call subprocess like this: The call method will execute the shell command.

There is no built-in mechanism that allows you to abort execution of an exec call. The closest thing we have is sys.exit(), but that exits the whole program, not just the exec. Fortunately, this can be worked around with a minor amount of exception handling boilerplate:

my_code = """
import sys

print("foo")

if True: 
    sys.exit()

print("bar")
"""

try:
    exec(my_code)
except SystemExit:
    pass
print('This is still executed')

# output:
# foo
# This is still executed

Chapter 20, exec() function is used for the dynamic execution of Python program which can Before using any methods inside the exec() function one must keep in mind  Stack Overflow Public questions and answers; Teams Private questions and answers for your team; Enterprise Private self-hosted questions and answers for your enterprise; Talent Hire technical talent

Just for fun, here's another way:

def breakable_exec(code):
    exec('for _ in [0]:' + '\n'.join("    " + line for line in code.splitlines()))

code = """
print("foo")

if True: 
    break

print("bar")
"""

breakable_exec(code)
# => foo

Stopping Code Execution In Python, Learning how to run shell commands in Python opens the door for us to automate python3 cd_return_codes.py `cd ~` ran with exit code 0 sh: line 0: cd:  In this article, we will look at the various ways to execute shell commands in Python, and the ideal situation to use each method. Using os.system to Run a Command. Python allows us to immediately execute a shell command that's stored in a string using the os.system() function.

Executing Shell Commands with Python, The exec() method executes the dynamically created program, which is either a string or a code object. When you run the program, the output will be: Enter a program: [print(item) for item in [1, 2, 3]] 1 2 3 If you allow users to input a value using exec(input()) , the user may issue commands to change file or even delete​  The exec () takes three parameters: locals (optional)- a mapping object. Dictionary is the standard and commonly used mapping type in Python. The use of globals and locals will be discussed later in the article. The exec () doesn't return any value, it returns None. When you run the program, the output will be:

Python exec(), Typical usage to run a program under control of the debugger is: mymodule.py"​, line 3, in test2 print(spam) NameError: spam >>> pdb.pm() > . next and step is that step stops inside a called function, while next executes called functions at  4. Execution model ¶ 4.1. Structure of a program ¶ A Python program is constructed from code blocks. A block is a piece of Python program text that is executed as a unit. The following are blocks: a module, a function body, and a class definition. Each command typed interactively is a block. A script file (a file given as standard input to

pdb — The Python Debugger, A script command (a command specified on the interpreter command line with the argument passed to the built-in functions eval() and exec() is a code block. Here only the sum, print and dir methods will be executed inside exec() function and not all built-in methods. This article is contributed by Chinmoy Lenka . If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org.

Comments
  • why are you using exec in the first place?
  • Why don't you want to use exceptions?
  • I don't want to use exceptions because I want to have an opportunity to keep the generated code readable.
  • @Fomalhaut well, unfortunately, this is what one would naturally use. What isn't readable about raise SomeException. Just wrap the whole thing in a function to keep things readable. Exceptions are idiomatic in Python.