Where to use a pyc file

Question

I want to know what a pyc file(python bytecode) is. I want to know all the details. I want to know about how pyc files interface with the compiler. Is it a replacement for e

Answer 1

To supplement Mike Graham's answer there are some interesting comments here giving some information on pyc files. Most interestingly I suspect for you is the line:

A program doesn't run any faster when it is read from a ‘.pyc’ or ‘.pyo’ file than when it is read from a ‘.py’ file; the only thing that's faster about ‘.pyc’ or ‘.pyo’ files is the speed with which they are loaded.

Which hits the nail on the head w.r.t. the crux of a pyc file. A pyc is a pre-interpreted py file. The python bytecode is still the same as if it was generated from a py file - the difference is that when using a pyc file you don't have to go through the process of creating that pyc output (which you do when running a py file). Read as you don't have to convert the python script to python bytecode.

If you've come across .class files in java this is a similar concept - the difference is in java you have to do the compiling using javac before the java interpreter will execute the application. Different way of doing things (the internals will be very different as they're different languages) but same broad idea.

Answer 2

From the docs:

As an important speed-up of the start-up time for short programs that use a lot of standard modules, if a file called spam.pyc exists in the directory where spam.py is found, this is assumed to contain an already-“byte-compiled” version of the module spam. The modification time of the version of spam.py used to create spam.pyc is recorded in spam.pyc, and the .pyc file is ignored if these don’t match.

See the ref for more info. But some specific answers:

The contents of the spam.pyc file are platform independent, so a Python module directory can be shared by machines of different architectures.

It's not an executable; it's used internally by the compiler as an intermediate step.

In general, you don't make .pyc files by hand: the interpreter makes them automatically.

Answer 3

Python bytecode requires Python to run, cannot be ran standalone without Python, and is specific to a particular x.y release of Python. It should be portable across platforms for the same version. There is not a common reason for you to use it; Python uses it to optimize out parsing of your .py file on repeated imports. Your life will be fine ignoring the existence of pyc files.