Is there a way to convert indentation in Python co

问题:

I am a totally blind programmer who would like to learn Python. Unfortunately the fact that code blocks are represented with different levels of indentation is a major stumbling block. I was wondering if there were any tools available that would allow me to write code using braces or some other code block delimiter and then convert that format into a properly indented representation that the Python interpreter could use?

回答1:

There's a solution to your problem that is distributed with python itself. pindent.py, it's located in the Tools\Scripts directory in a windows install (my path to it is C:\Python25\Tools\Scripts), it looks like you'd have grab it from svn.python.org if you are running on Linux or OSX.

It adds comments when blocks are closed, or can properly indent code if comments are put in. Here's an example of the code outputted by pindent with the command:

pindent -c myfile.py

def foobar(a, b):
   if a == b:
       a = a+1
   elif a < b:
       b = b-1
       if b > a: a = a-1
       # end if
   else:
       print 'oops!'
   # end if
# end def foobar

Where the original myfile.py was:

def foobar(a, b):
   if a == b:
       a = a+1
   elif a < b:
       b = b-1
       if b > a: a = a-1
   else:
       print 'oops!'

You can also use pindent.py -d to insert the correct indentation based on comments (read the header of pindent.py for details), this should allow you to code in python without worrying about indentation.

I'd be interested to learn what solution you end up using, if you require any further assistance, please comment on this post and I'll try to help.

回答2:

Python supports braces for defining code blocks, and it also supports using 'begin' and 'end' tags.

Please see these code examples:

class MyClass(object): #{
    def myfunction(self, arg1, arg2): #{
        for i in range(arg1): #{ 
            print i
        #}
    #}
#}

And an example with bash style:

fi = endclass = enddef = endclass = done = None
class MyClass(object):
    def myfunction(self, arg1, arg2):
        for i in range(arg1): #do
            if i > 5: #then
                print i
            fi
        done
    enddef
endclass

The best thing about this is is that you can forget to put a close bracket in, and it's still valid python!

class MyClass(object): #{
    def myfunction(self, arg1, arg2): #{
        for i in range(arg1): #{ 
            print i
        # whoops, forgot to close that bracket!
    #}
#}

original gag

My real advice is to get a Braille display if you can afford one/source one - blind python programmers of my acquaintance really found a Braille display indispensable for writing python programs, it makes the indentation thing much less painful. A 40 cell display is well worth it.

回答3:

I personally doubt that there currently is at the moment, as a lot of the Python afficionados love the fact that Python is this way, whitespace delimited.

I've never actually thought about that as an accessibility issue however. Maybe it's something to put forward as a bug report to Python?

I'd assume that you use a screen reader here however for the output? So the tabs would seem "invisible" to you? With a Braille output, it might be easier to read, but I can understand exactly how confusing this could be.

In fact, this is very interesting to me. I wish that I knew enough to be able to write an app that will do this for you.

I think it's definately something that I'll put in a bug report for, unless you've already done so yourself, or want to.

Edit: Also, as noted by John Millikin There is also PyBraces Which might be a viable solution to you, and may be possible to be hacked together dependant on your coding skills to be exactly what you need (and I hope that if that's the case, you release it out for others like yourself to use)

Edit 2: I've just reported this to the python bug tracker

回答4:

Although I am not blind, I have heard good things about Emacspeak. They've had a Python mode since their 8.0 release in 1998 (they seem to be up to release 28.0!). Definitely worth checking out.

回答5:

You should be able to configure your editor to speak the tabs and spaces -- I know it's possible to display whitespace in most editors, so there must be an accessibility option somewhere to speak them.

Failing that, there is pybraces, which was written as a practical joke but might actually be useful to you with a bit of work.

回答6:

If you're on Windows, I strongly recommend you take a look at EdSharp from: http://empowermentzone.com/EdSharp.htm It supports all of the leading Windows screenreaders, it can be configured to speak the indentation levels of code, or it has a built in utility called PyBrace that can convert to and from braces syntax if you want to do that instead, and it supports all kinds of other features programmers have come to expect in our text editors. I've been using it for years, for everything from PHP to JavaScript to HTML to Python, and I love it.

回答7:

I appreciate your problem, but think you are specifying the implementation instead of the problem you need solved. Instead of converting to braces, how about working on a way for your screen reader to tell you the indentation level?

For example, some people have worked on vim syntax coloring to represent python indentation levels. Perhaps a modified syntax coloring could produce something your screen reader would read?

回答8:

All of these "no you can't" types of answers are really annoying. Of course you can.

It's a hack, but you can do it.

http://timhatch.com/projects/pybraces/

uses a custom encoding to convert braces to indented blocks before handing it off to the interpreter.

---

As an aside, and as someone new to python - I don't accept the reasoning behind not even allowing braces/generic block delimiters ... apart from that being the preference of the python devs. Braces at least won't get eaten accidentally if you're doing some automatic processing of your code or working in an editor that doesn't understand that white space is important. If you're generating code automatically, it's handy to not have to keep track of indent levels. If you want to use python to do a perl-esque one-liner, you're automatically crippled. If nothing else, just as a safeguard. What if your 1000 line python program gets all of its tabs eaten? You're going to go line-by-line and figure out where the indenting should be?

Asking about it will invariably get a tongue-in-cheek response like "just do 'from __ future __ import braces'", "configure your IDE correctly", "it's better anyway so get used to it" ...

I see their point, but hey, if i wanted to, i could put a semicolon after every single line. So I don't understand why everyone is so adamant about the braces thing. If you need your language to force you to indent properly, you're not doing it right in the first place.

Just my 2c - I'm going to use braces anyway.

回答9:

I use eclipse with the pydev extensions since it's an IDE I have a lot of experience with. I also appreciate the smart indentation it offers for coding if statements, loops, etc. I have configured the pindent.py script as an external tool that I can run on the currently focused python module which makes my life easier so I can see what is closed where with out having to constantly check indentation.

回答10:

Searching an accessible Python IDE, found this and decided to answer. Under Windows with JAWS:

1. Go to Settings Center by pressing JawsKey+6 (on the number row above the letters) in your favorite text editor. If JAWS prompts to create a new configuration file, agree.
2. In the search field, type "indent"
3. There will be only one result: "Say indent characters". Turn this on.
4. Enjoy!

The only thing that is frustrating for us is that we can't enjoy code examples on websites (since indent speaking in browsers is not too comfortable — it generates superfluous speech).

Happy coding from another Python beginner).

回答11:

There are various answers explaining how to do this. But I would recommend not taking this route. While you could use a script to do the conversion, it would make it hard to work on a team project.

My recommendation would be to configure your screen reader to announce the tabs. This isn't as annoying as it sounds, since it would only say "indent 5" rather than "tab tab tab tab tab". Furthermore, the indentation would only be read whenever it changed, so you could go through an entire block of code without hearing the indentation level. In this way hearing the indentation is no more verbose than hearing the braces.

As I don't know which operating system or screen reader you use I unfortunately can't give the exact steps for achieving this.

回答12:

Edsger Dijkstra used if ~ fi and do ~ od in his "Guarded Command Language", these appear to originate from the Algol68. There were also some example python guarded blocks used in RosettaCode.org.

fi = od = yrt = end = lambda object: None;
class MyClass(object):
    def myfunction(self, arg1, arg2):
        for i in range(arg1) :# do
            if i > 5 :# then
                print i
            fi
        od # or end(i) #
    end(myfunction)
end(MyClass)

Whitespace mangled python code can be unambiguously unmangled and reindented if one uses guarded blocks if/fi, do/od & try/yrt together with semicolons ";" to separate statements. Excellent for unambiguous magazine listings or cut/pasting from web pages.

It should be easy enough to write a short python program to insert/remove the guard blocks and semicolons.