Rationale for read-only property of co_code

[João Neves]

On Apr 2, 4:35 pm, castiro... at gmail.com wrote:
> Are Python bytes codes Python byte codes?

I'm not quite sure I understood your question, sorry.

> Do you foresee any machine-dependent optimizations?

In my personal case, I am not looking for optimizations in the
generated bytecode.

Let me give a very basic example. Say we have these two functions:

def inc(x):
   x = x + 1

def dec(x):
   x = x - 1

Examining the compiled bytecodes for these two functions:

>>> inc.func_code.co_code
'|\x00\x00d\x01\x00\x17}\x00\x00d\x00\x00S'

>>> dec.func_code.co_code
'|\x00\x00d\x01\x00\x18}\x00\x00d\x00\x00S'

Now suppose that I wanted to mess with inc, and have it behave like
dec.

For that, I would like to do something like this, for instance:

>>> inc.func_code.co_code = '|\x00\x00d\x01\x00\x18}\x00\x00d\x00\x00S'

Of course, as of this moment, I get a TypeError exception, because
co_code is read-only.

The thing I've been wondering is why _is_ it read-only? In what
circumstances having write access to co_code would break the language
or do some other nasty stuff?

João Neves