Installing Python 3.7.4 from source

Chenglu — Sat, 22 Feb 2020 04:12:38 +0000

I keep installing the Python from source, for two reason:

More flexibility to manage. Cause I decide where to install it, which python module to enable.
Chose the latest version. Python comes from system package manager is sometimes a older version.

Download Python source code.

wget https://www.python.org/ftp/python/3.7.4/Python-3.7.4.tgz
mkdir ~/.python3
mv Python-3.7.4.tgz ~/.python3
cd ~/.python3
tar -zxvf Python-3.7.4.tgz

Install dependencies

sudo apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libreadline-dev libffi-dev

Enable ssl module

vim ~/.python3/Python-3.7.4/Modules/Setup.dist

find keyword ssl and uncomment this lines:

# SSL=/usr/local/ssl
# _ssl _ssl.c \
#         -DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \
#         -L$(SSL)/lib -lssl -lcrypto

Compile and install

./configure --prefix=/root/.python3/ --with-ensurepip
make
make install

Add bin to PATH

Now the python3 and pip binary are located at ~/.python3/bin, you can add the directory to $PATH to access those commands directly.

A way to solve the handler mess of Tornado

Chenglu — Fri, 21 Feb 2020 15:35:39 +0000

As a web developer comming from Ruby on Rails, the "flexibility" of the handlers organization in Tornado is really painful. So I decide to organize the handlers in a Rails way.

By default, in Tornado, the actions of a handler are exactly the http verb: GET, POST, PATCH, DELETE. So when I think about how to write a handler, I have to think in the protocol layer.

For example, building a websites of books. The books list page and book detail page both use the same http verb GET, but they have totally different logic in the backend. If we organize the handler in http verb, then the handler goese like this:

class BooksHandler(RequestHandler):

    def get(self, id=None):
        if id is not None:
            # render book list page
        else:
            # render book detail of id

Wouldn't that be great if we could just seperate the 2 unrelated pieces of code into 2 methods, like the following:

class BooksHandler(RequestHandler):

    def index(self):
        # render book list page

    def show(self, id):
        # render book detail of id

And that is the main goal of the refactoring, to organize the handlers in a Resource way instead of Protocol way.

Luckly Ruby on Rails already done this before and have been proved to be practisable even in large projects. So I'm just gonna copy the resource abstraction of Rails, that is:

A Handler is for manumating one resource.
A Handler can have at most 7 actions. The following table shows what the action should do and how does a http request reach them.

HTTP Verb	Path	Handler#Action	Used for
GET	/photos	photos#index	display a list of all photos
GET	/photos/new	photos#new	return an HTML form for creating a new photo
POST	/photos	photos#create	create a new photo
GET	/photos/:id	photos#show	display a specific photo
GET	/photos/:id/edit	photos#edit	return an HTML form for editing a photo
PATCH/PUT	/photos/:id	photos#update	update a specific photo
DELETE	/photos/:id	photos#destroy	delete a specific photo

Then What about login? I don't see any resources in that action.

Everything can be resources. For login/logout, it's actually create a session and destroy a session.

Now if we organizing our handlers in this way, there is no need for us to write the router's url matcher manully, a handler should populate the routes by itself, like these:

class BooksHandler(RequestHandler):

    def index(self):
        # render book list page

    def show(self, id):
        # render book detail of id


app = tornado.web.Application([
    # no more manully set regex
    *BooksHandler.routes()
])
app.listen(8888)
tornado.ioloop.IOLoop.current().start()

Now, it should be good to visit the 2 url:

curl http://localhost:8888/books
curl http://localhost:8888/books/1

I have already implemented this at https://github.com/louis-she/tornado-resource-handler. This can be directly used in existed projects, just try to write new handler in resource way, it will not broke the existing handlers.

Have fun with abstracting Resources.