How to predefine a python variable

Question

The following code work but it's little bit messy and most of IDE show an error for undefined variable => "myFile" even if the code works.

i = 0
block = False
while i < 10:
   if block == True:
      myFile.write("End of a Turn.")
   block = True
   myFile = open("path/of/my/file/"+str(i)+".txt", "w")
   myFile.write("The turn begin.")
   i += 1

What I want to do is to "pre-define" the variable before the first assignment:

#myFile = SOMETHING_THAT_DOES_NOT_RUIN_THE_FOLLOWING_CODE
myFile = None #RESOLVE
i = 0
block = False
while i < 10:
   if block == True:
      myFile.write("End of a Turn.")
   block = True
   myFile = open("path/of/my/file/"+str(i)+".txt", "w")
   myFile.write("The turn begin.")
   i += 1

To avoid some IDE comprehension problems.

Ty for help,

S.

timgeb · Accepted Answer · 2014-06-03 10:09:07Z

1

You can do it like this.

myFile = None
i = 0
block = False
while i < 10:
   if block and myFile:
       # ...

Or, probably cleaner:

for i in range(9):
    with open(str(i) + '.txt', 'w') as myFile:
        myFile.write('The turn begin. End of a turn')
with open(str(i + 1) + '.txt', 'w') as myFile:
        myFile.write('The turn begin.')

edited Jun 3, 2014 at 10:09

answered Jun 3, 2014 at 9:50

timgeb

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1 Comment

timgeb Over a year ago

@user3675596 I added an alternative version. You can get rid of the block variable, also manually incrementing i is not necessary.

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