How to solve local variable 'f' referenced before assignment in file

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I am facing problem in error in my programs

I am not able to understand what I am doing mistake .

What I have tried:

def Runcommand(self, data):
      command = data
      #command = self.read()
      stdoutOrigin=sys.stdout
      try:
          sys.stdout = open("command1.txt", "w")
          exec(command)
          sys.stdout=stdoutOrigin
          with open("command1.txt","r") as f:
              result =  f.read()
              print(result)
              self.write(result.encode())
      except Exception as e:
          s=str(e)
          error=''.join((s,'\n'))
          self.write(error.encode())
      finally:
          f.close()

error was

local variable 'f' referenced before assignment

Posted 4-Sep-22 19:40pm

HelpMewithCode

Updated 4-Sep-22 20:50pm

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OriginalGriff · Answer 1 · 2022-09-04T20:50:00

When you create a variable, it has Scope - it is only visible or usable within the block it is created in.
Wo when you create a variable called f inside a try block, it's scope is restricted to the block, and it cannot be referenced outside it as it is destroyed when you leave the block by whatever method. To access it outside the try block, you would have to declare f before the try statement, at which point it is accessible to all code in the method.

In fact, the with statement automatically closes the file when you exit the with block for you, so the whole finally block is redundant, and can be removed - which solves the problem more neatly!