| OSCon Day 1 |
[Jul. 21st, 2008|10:57 pm] |
Andrew and I arrived for registration and took advantage of the
continental breakfast before heading up to the Intro to Python.
O'Reilly had the registration process pretty streamlined. They had a
long bank of laptops wich you needed only enter your registration
code, or your email address (if you registered on the oscon conference
web site). Register, then walk up to the materials station and pick
up your ID and badge card.
There were plenty of juices, coffee, fruit and pastries. There was
also plenty of seating. To either O'Reilly's or the Oregon Conference
Center's credit, things were very well organized.
The conference room we were must have had seating for a few hundred
people and it was effectively full. There was limited space for each
attendee and their items (it was at least cramped for me) - though
they expected a laptop per attendee - there were plenty of power
strips, laid along every other row of tables, within easy reach of
every single seat. It was well planned and laid out.
The intro to Python got underway at 8:30 and although it was geared
toward an audience with some programming experience, it assumed (as
the title suggested) no python experience. Steve Holden was a great
speaker, filling in twice with anecdotes while technical issues were
worked out with equipment (once was a mis configuration of his laptop,
the other was a power interruption).
Python is a very capable language. It is more consistent about its
OO and syntax when compared to Perl. It is also a lot bigger on
conventions, broadly adopted by the community. This is mostly focused
on formatting (one expression per line), in-line documentation and
coding stle in general.
Functions are first class types, you can take a function into a
variable, you can implement the equivalent of funcall and apply in
python. Functions can be passed as arguments. Python supports
positional parameters, default values for function params and calling
functions, any function, with positional arguments, named arguments, a
tuple of arguments (similar to funcall), or a dictionary (an indirect
way of using named arguments).
Python actually has a lot of features which were inspired by
functional programming (including list comprehensions).
Python is byte-compiled, like Java. You write code in a .py file, and
the first time it is loaded as a module (import), python compiles the
code for you. The time stamp check fo the .pyc vs the .py file is
transparent, it's automatically handled.
Strings are immutable, which is something that helps Jython be a
natural fit in the JVM.
Python supports some destructuring constructs, based in what it calls
tuples. It's easier to show an example:
a, (b, c) = (1, (2, 3))
print a,b,c => 1, 2, 3
Tuples, and this kind of binding syntax, is widely used in processing
things like lists, and maps.
An interesting feature of the language is the pair of functions,
local() and gobal(). local() returns a dictionary (Python's name for
a Map), of all of the variable bindings (and values) that are visible
in the current scope (exclusive of global variables). globals()
returns the variables in the entire module's scope (not local, lexical
or class scope, and not global in the sense of a Perl global - not
universally global).
Other highlights:
- the yield() form, which is like a weak kind of continuation
- for, and while loops can have an else clause, which is executed
when the form terminates normally (as opposed to breaking out
of the loop)
- the Python try/catch form (try/except/finally) can have an else
form, again, which is executed if no exception was thrown in
the try block
After a break for lunch, both Andrew and I attended the Introduction
to Django, presented by Jacob Kaplan-Moss.
Django is an MVC framework for Python for rapid development of
interactive web sites. It is an MVC framework very much in the spirit
of Ruby on Rails - I've done a small site in Rails and the parallels
were very close between the two frameworks.
Django has a code generation framework, an ORM layer (which is very
similar to Rails' ActiveRecord), an html template system (with a
default syntax based on PHPs smarty template system), and integrated
support for testing.
Django has an interesting testing feature called doctests. If you've
worked with an interactive language with a REPL, you have probably
used it to explore the behavior of code and to informally test the
code. Doctests are a way of (almost literally) taking a cut and paste
of the interactive session and vivifying the transcript as a
regression test. I like the idea of a recorded test, but as Andrew
and I talked about it, he convinced me that the literal representation
wasn't all that great a choice for implementing those kinds of tests.
I do like the reduction of effort that comes with that kind of
testing, and recognize the inherent informality of it.
All that said, Django (like Rails) is big on doing test driven
development.
I looked up the status of Django on Jython and apparently it's close
to being a 1.0 release (nothing I'd recommend for use at HMS at the
moment, but Sun has hired people to work on Jython and Django is one
of the frameworks they are concerned with making work).
I'm looking forward to tomorrow. |
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