There are cases that you don’t want Python interpreter to write bytecode. For example, you are too lazy to use some format for configuration file. Instead, you use Python code as the configuration. Generally, it will be fine, just little annoying when there is bytecode written alongside the configuration file.
If you don’t like, you can turn it off. There are two ways to do so:
- Running Python interpreter with -B option or
- Setting sys.dont_write_bytecode to True.
These two options only work for Python 2.6+, it also work in Python 3, no bytecode will be written in __pycache__ directory.
Here is a demostration script:
import glob import imp import sys sys.path.append('/tmp') print('sys.dont_write_bytecode = %s' % sys.dont_write_bytecode) print('') # module testimport with open('/tmp/testimport.py', 'w') as f: pass print('importing /tmp/testimport.py') import testimport print(testimport) print('') sys.dont_write_bytecode = True print('sys.dont_write_bytecode = %s' % sys.dont_write_bytecode) print('') # module testimport2 with open('/tmp/testimport2.py', 'w') as f: pass print('importing /tmp/testimport2.py') import testimport2 print(testimport2) print('') # module prog.conf with open('/tmp/prog.conf', 'w') as f: pass print('importing /tmp/prog.conf') conf = imp.load_source('prog_conf', '/tmp/prog.conf') print(conf) print('') print('/tmp/*c: %s' % glob.glob('/tmp/*c')) #**/
sys.dont_write_bytecode = False importing /tmp/testimport.py <module 'testimport' from '/tmp/testimport.py'> sys.dont_write_bytecode = True importing /tmp/testimport2.py <module 'testimport2' from '/tmp/testimport2.py'> importing /tmp/prog.conf <module 'prog_conf' from '/tmp/prog.conf'> /tmp/*c: ['/tmp/testimport.pyc']
Only module testimport‘s bytecode is written. The setting dont_write_bytecode affects any importing function as you can see imp.load_source does not result a bytecode /tmp/prog.confc written.
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