Bare words / new keywords in Python

问题:

I wanted to see if it was possible to define new keywords or, as they're called in WAT's Destroy All Software talk when discussing Ruby, bare words, in Python.

I came up with an answer that I couldn't find elsewhere, so I decided to share it Q&A style on StackOverflow.

回答1:

I've only tried this in the REPL, outside any block, so far. It may be possible to make it work elsewhere, too.

I put this in my python startup file:

def bareWordHandler(type_, value, traceback_):
    if isinstance(value, SyntaxError):
        import traceback

        # You can probably modify this next line so that it'll work within blocks, as well as outside them:
        bareWords = traceback.format_exception(type_, value, traceback_)[1].split()

        # At this point we have the raw string that was entered.
        # Use whatever logic you want on it to decide what to do.
        if bareWords[0] == 'Awesome':
            print(' '.join(bareWords[1:]).upper() + '!')
            return
    bareWordsHandler.originalExceptHookFunction(type_, value, traceback_)

import sys
bareWordsHandler.originalExceptHookFunction = sys.excepthook
sys.excepthook = bareWordsHandler

Quick REPL session demonstration afterwords:

>>> Awesome bare words
BARE WORDS!

Use responsibly.

Edit: Here's a more useful example. I added in a run keyword.

if bareWords[0] == 'from' and bareWords[2] == 'run':
        atPrompt.autoRun = ['from ' + bareWords[1] + ' import ' + bareWords[3].split('(')[0],
                            ' '.join(bareWords[3:])]
        return

atPrompt.autoRun is a list of variables that, when my prompt is displayed, will automatically be checked and fed back. So, for example, I can do this:

>>> from loadBalanceTester run loadBalancerTest(runJar = False)

And this gets interpreted as:

from loadBalancerTest import loadBalancerTest
loadBalancerTest(runJar = False)

It's kind of like a macro - it's common for me to want to do this kind of thing, so I decided to add in a keyword that lets me do it in fewer keystrokes.