How to get return value of exec?

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How would I do the following:

What I have tried:

resp=  'a = 4; print(\"Expected a = 4. Actual a = {} \".format(a))'
rest = exec(resp)
print(rest)
Output:None

How do i store my return value in rest ?

Posted 16-Aug-22 23:13pm

HelpMewithCode

Updated 16-Aug-22 23:44pm

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Richard MacCutchan · Answer 1 · 2022-08-16T23:44:00

Solution 2

As explained at Built-in Functions — Python 3.10.6 documentation[^], the return value of the exec function is always None. So your Python script will need to pipe its output into a file which you can then read. Something like:

Python

resp='a = 4; rest = "Expected a = 4. Actual a = {} ".format(a); f = open("foo.txt", "w"); f.write(rest)'
exec(resp)

Posted 16-Aug-22 23:44pm

Richard MacCutchan

Comments

Richard MacCutchan 18-Aug-22 3:52am

What is the problem?

Richard MacCutchan 18-Aug-22 4:54am

So what is the problem? And why not use the solution I gave you in my latest comment to your other question at How to capture output from Python interpreter ?[^]?

HelpMewithCode 18-Aug-22 5:13am

You have given thats worked fine with one command .If its multiple command den its wont work

so tried to used file concept ..write to the file and read again
if write above code about file concept , its just write the txt file , but how do i read from the file

Richard MacCutchan 18-Aug-22 5:18am

See 7. Input and Output — Python 3.10.6 documentation[^]. You really need to make use of the documentation where everything is explained.

OriginalGriff · Answer 2 · 2022-08-16T23:40:00

exec has no return value: Built-in Functions — Python 3.10.6 documentation[^] - it always returns None

The code you are executing doesn't even try to return anything. If it did, it would fail:

Quote:
Be aware that the nonlocal, yield, and return statements may not be used outside of function definitions even within the context of code passed to the exec() function.

How to get return value of exec?

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How to get return value of exec?

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