Python 2to3 tool is another important parameter used by different programmers in performing different tasks. Learn more about it here.
Python 2to3 tool
Parameter
filename / directory_name
Option
-f FIX, –fix=FIX
-j PROCESSES, –processes=PROCESSES -x NOFIX, –nofix=NOFIX -l, –list-fixes
-p, –print-function
-v, –verbose
–no-diffs
-w
-n, –nobackups
-o OUTPUT_DIR, --output-dir=OUTPUT_DIR
-W, --write-unchanged-files --add-suffix=ADD_SUFFIX
Description
2to3 accepts a list of files or directories which is to be transformed as its argument. The directories are recursively traversed for Python sources.
Option Description
Specify transformations to be applied; default: all. List available transformations with –list-fixes
Run 2to3 concurrently
Exclude a transformation
List available transformations
Change the grammar so that print() is considered a function More verbose output
Do not output diffs of the refactoring
Write back modified files
Do not create backups of modified files
Place output files in this directory instead of overwriting input files. Requires the -n flag, as backup files are unnecessary when the input files are not modified.
Write output files even is no changes were required. Useful with -o so that a complete source tree is translated and copied. Implies -w.
Specify a string to be appended to all output filenames. Requires -n if non-empty. Ex.: --add-suffix='3' will generate .py3 files.
Basic Usage
Consider the following Python2.x code. Save the file as example.py
Python 2.x Version ≥ 2.0
def greet(name):
print "Hello, {0}!".format(name)
print "What's your name?"
name = raw_input()
greet(name)
In the above file, there are several incompatible lines. The raw_input() method has been replaced with input() in Python 3.x and print is no longer a statement, but a function. This code can be converted to Python 3.x code using the 2to3 tool.
Unix
$ 2to3 example.py
Windows
path/to/2to3.py example.py
Running the above code will output the differences against the original source file as shown below.
RefactoringTool: Skipping implicit fixer: buffer
RefactoringTool: Skipping implicit fixer: idioms
RefactoringTool: Skipping implicit fixer: set_literal
RefactoringTool: Skipping implicit fixer: ws_comma
RefactoringTool: Refactored example.py
--- example.py (original)
+++ example.py (refactored)
@@ -1,5 +1,5 @@
def greet(name):
print "Hello, {0}!".format(name) -print "What's your name?"
-name = raw_input()
print("Hello, {0}!".format(name)) +print("What's your name?")
+name = input() greet(name)
RefactoringTool: Files that need to be modified:
RefactoringTool: example.py
The modifications can be written back to the source file using the -w flag. A backup of the original file called example.py.bak is created, unless the -n flag is given.
Unix
$ 2to3 -w example.py
Windows
path/to/2to3.py -w example.py
Now the example.py file has been converted from Python 2.x to Python 3.x code.
Once finished, example.py will contain the following valid Python3.x code:
Python 3.x Version ≥ 3.0
def greet(name):
print("Hello, {0}!".format(name))
print("What's your name?")
name = input()
greet(name)