Keystone: Python Web Development, Simplified

ABOUT DATE BY 2012-03-20 DAN CROSTA (@LAZLOFRUVOUS) KEYSTONE PYTHON WEB
DEVELOPMENT, SIMPLIFIED

Question: Can Python be as easy as PHP?

Question: ... without the pitfalls?

Deﬁne: Pitfall • Mixed logic + markup • No namespaces
• Performance issues • Security is an afterthought • Dollar signs

Deﬁne: Easy • Drop-in upgrades • No URL mapping •
Run everywhere • Progressive enhancement • No setup*

Keystone: All Python up front, HTML party in the back.

Keystone by Example <!doctype html> <html> <head> <title>Hello from Keystone</title>
</head> <body> <h1>Hello, world</h1> </body> </html>

Keystone by Example {% set greeting = "Hello" %} <!doctype
html> <html> <head> <title>{{greeting}} from Keystone</title> </head> <body> <h1>Hello, world</h1> </body> </html>

Keystone by Example import random greeting = random.choice(['Hello', 'Goodbye']) name
= random.choice(['World', 'Moon']) ---- <!doctype html> <html> <head> <title>{{greeting}} from Keystone</title> </head> <body> <h1>{{greeting}}, {{name}}</h1> </body> </html>

Keystone by Example import pymongo db = pymongo.Connection()['test'] rslt =
db.greetings.find_one() ---- <!doctype html> <html> <head> <title>{{rslt.greeting}} from Keystone</title> </head> <body> <h1>{{rslt.greeting}}, {{rslt.name}}</h1> </body> </html>

Keystone by Example import pymongo, gridfs db = pymongo.Connection()['test'] storage
= gridfs.GridFS() fileobj = gridfs.get_latest_version('image.png') header('Content-Type', 'image/png') return_response(fileobj) ----

Paths are URLs + $APP/ + about.html + index.ks +
static/ | + style.css | + script.js + %username.ks + %username/ + profile.ks /about.html /, /index /static/style.css /static/script.js /dcrosta /dcrosta/profile

Behind the Scenes def parse(self, fileobj): first, second = [],
[] active = first for lineno, line in enumerate(fileobj): if line.strip() == '----': if active is second: raise InvalidTemplate( 'Line %d: separator already seen' % lineno) active = second else: active.append(line) viewcode_str = ''.join(first) viewcode, viewglobals = self.compile(viewcode_str, fileobj.name) def viewfunc(viewlocals): exec viewcode in viewglobals, viewlocals return viewlocals return viewfunc

Behind the Scenes def compile(self, viewcode_str, filename): viewcode = compile(viewcode_str,
filename, 'exec') viewglobals = {} for stmt in compiler.parse(viewcode_str).node: if isinstance(stmt, Import): modname, asname = stmt.names[0] if asname is None: asname = modname viewglobals[asname] = __import__(modname) # else ... return viewcode, viewglobals

Behind the Scenes def compile(self, viewcode_str, filename): viewcode = compile(viewcode_str,
filename, 'exec') viewglobals = {} for stmt in compiler.parse(viewcode_str).node: # if ... elif isinstance(stmt, From): fromlist = [x[0] for x in stmt.names] mod = __import__(stmt.modname, {}, {}, fromlist) for name, asname in stmt.names: if name == '*': for asname in getattr(mod, '__all__', dir(mod)): viewglobals[asname] = getattr(mod, asname) else: if asname is None: asname = name viewglobals[asname] = getattr(mod, name) return viewcode, viewglobals

Behind the Scenes def render_keystone(self, request, template): response = Response(mimetype='text/html')
viewlocals = { 'request': request, 'headers': response.headers, # ... } try: response.response = self.engine.render(template, viewlocals) except HTTPException, ex: return ex.get_response(request.environ) return response def render(self, template, viewlocals): jinja_template = jinja_env.get_template(template.name) return jinja_template.generate(**template.viewfunc(viewlocals))

Other Goodies • PaaS support keystone --configure {heroku,dotcloud,epio} • Run
code at startup startup.py • HTTP Methods request.method == "POST" • HTTP Errors raise NotFound() • Cookies set_cookie(), delete_cookie()

Get Keystone • PyPI pip install Keystone • Source at
Github https://github.com/dcrosta/keystone • Documentation http://keystone.readthedocs.org/

Keystone: Python Web Development, Simplified

Keystone: Python Web Development, Simplified

dcrosta

More Decks by dcrosta

Other Decks in Programming

Featured

Transcript

ABOUT DATE BY 2012-03-20 DAN CROSTA (@LAZLOFRUVOUS) KEYSTONE PYTHON WEB

Question: Can Python be as easy as PHP?

Question: ... without the pitfalls?

Deﬁne: Pitfall • Mixed logic + markup • No namespaces

Deﬁne: Easy • Drop-in upgrades • No URL mapping •

Keystone: All Python up front, HTML party in the back.

Keystone by Example <!doctype html> <html> <head> <title>Hello from Keystone</title>

Keystone by Example {% set greeting = "Hello" %} <!doctype

Keystone by Example import random greeting = random.choice(['Hello', 'Goodbye']) name

Keystone by Example import pymongo db = pymongo.Connection()['test'] rslt =

Keystone by Example import pymongo, gridfs db = pymongo.Connection()['test'] storage

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Paths are URLs + $APP/ + about.html + index.ks +

Behind the Scenes def parse(self, fileobj): first, second = [],

Behind the Scenes def compile(self, viewcode_str, filename): viewcode = compile(viewcode_str,

Behind the Scenes def compile(self, viewcode_str, filename): viewcode = compile(viewcode_str,

Behind the Scenes def render_keystone(self, request, template): response = Response(mimetype='text/html')

Other Goodies • PaaS support keystone --configure {heroku,dotcloud,epio} • Run

Get Keystone • PyPI pip install Keystone • Source at