I have two python files. From python file #1, I want to check to see if there is a certain global variable defined in python file #2.
What is the best way to do this?
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3 Answers
You can directly test whether the file2 module (which is a module object) has an attribute with the right name:
import file2
if hasattr(file2, 'varName'):
# varName is defined in file2…
This may be more direct and legible than the try… except… approach (depending on how you want to use it).
2 Comments
DirtyBit
Could we also get its value?
Eric O. Lebigot
@Yuval Adam's
try solution would be the way to go.try:
from file import varName
except ImportError:
print 'var not found'
Alternatively you could do this (if you already imported the file):
import file
# ...
try:
v = file.varName
except AttributeError:
print 'var not found'
This will work only if the var is global. If you are after scoped variables, you'll need to use introspection.
7 Comments
paassno
Is it OK to put in import statement in the middle of the code? By OK I mean not bad convention.
Yuval Adam
Sure, it's totally acceptable to defer module loading to a later stage.
Yuval Adam
You could also just
import file at the beginning, and later on check for file.varName, exactly the same way.paassno
Alrite your comment is exactly what I needed.
paassno
I do have a problem in the script. For some reason, it goes into the try statement, passes, then goes to the except statement?
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With the getattr() built-in function you also can specify a default value like:
import file2
myVar = getattr(file2, attribute, False)
See the documentation
2 Comments
Eric O. Lebigot
This does not generally answer the original question: what if the variable exists and is false?
locose
Then the answer would be False anyway so still correct although i see what your saying