What does this code mean: “print >> sys.stderr”

问题:

print >> sys.stderr, "Error in atexit._run_exitfuncs:" 

Why print '>>' in front of sys.stderr?

Thanks.

回答1:

This syntax means writes to a file object (sys.stderr in this case) instead of standard output. [Link]

In Python 3.0, print becomes a function instead of a statement: [Link]

print("Error in atexit._run_exitfuncs:", file=sys.stderr) 

回答2:

From the Python documentation:

print also has an extended form, defined by the second portion of the syntax described above. This form is sometimes referred to as “print chevron.” In this form, the first expression after the >> must evaluate to a “file-like” object, specifically an object that has a write() method as described above. With this extended form, the subsequent expressions are printed to this file object. If the first expression evaluates to None, then sys.stdout is used as the file for output.

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