[workshop] lesson 00: "hello %s!"

[Dan Geiser]

OK, this question might seem a little "after the fact" but how does one get
startes setting up Python so we can actually take advantages of these
lessons which Michal is going to teach us?

Thanks,
Dan mailto:dgeiser13@hotmail.com

----- Original Message -----
From: "Michal Wallace" <michal@sabren.com>
To: <workshop@cornerhost.com>
Cc: <workshop-lite@cornerhost.com>
Sent: Saturday, May 04, 2002 11:28 PM
Subject: [workshop] lesson 00: "hello %s!"


> ############################################################
> ## Hey all,
> ##
> ## I've got friends in town this week, so I'm off to a slow
> ## start here. :) I'm new at this, so let me know if I'm
> ## moving too fast/slow/etc with this tutorial...
> ##
> ## Anyway, here goes!
> ##
> ## -Michal
> ############################################################
>
> ## lesson 00: "hello, %s!" #################################
>
> * Hello, World!
>
> The traditonal introduction to a computer language is the
> "Hello, World!" program. In python, it's a one-liner:
>
> ###
> print "hello, world!"
> ###
>
> Easy, huh? If you load up a python interpreter and type
> that line, it'll print "hello, world!" to the screen.
>
> * The Response Object
>
> Web apps don't print their output to a screen, but send it across the
> internet. For this reason (and others I'll go into later on), we
> redirect the output to a response object. In the framework that I use,
> this object is called RES:
>
> ###
> print >> RES, "hello, world!"
> ###
>
>
> That's it! Our first web application!
>
> So how can we see it work?
>
> To run this on a cornerhost server, put it in a text file with the
> extension ".app". Call this one "hello.app" and upload it to your
> account.
>
> Now load it in your browser as if it were a normal web page.  If all
> goes well, you should see:
>
>    hello, world!
>
>
> If you get an error message, double check that you have the filename
> correct and that the file contains no leading tabs or spaces - python
> has very strict rules about whitespace.
>
> * Hello, NAME!
>
> Let's personalize our greeting a bit. Python lets us insert a variable
> (a defined value) into our output by using the percent sign:
>
> ###
> name = "Orville"
> print >> RES, "hello, %s!" % name
> ###
>
> If you upload this script and load it in the browser, the
> result should be:
>
>
>    hello, Orville!
>
> * The Request Object
>
> Of course, most of the people using your app won't be named
> Orville. One way of passing a name into our app would be to include it
> in the query string:
>
>
>    http:// ... /hello.app?name=Gomer
>
>
> We can read the query string with the REQ (Request) object:
>
> ###
> name = REQ.get("name")
> ###
>
> Better yet, we can provide a default:
>
> ###
> name = REQ.get("name", "whoever you are")
> print >> RES, "hello, %s!" % name
> ###
>
> Try running this with and without a "?name=whatever"
> appended to the url.
>
> * Adding a Form
>
> But why settle for a default, when we can simply ask users what their
> names are? This next example uses the REQ.has_key() method to tell if
> a name has been passed in. If so, it says hello. If not, it shows an
> HTML form:
>
> ###
> if REQ.has_key("name"):
>     print >> RES, "hello, %s!" % REQ.get("name")
> else:
>     # notice the single quotes, to prevent conflict with HTML:
>     print >> RES, '<form action="hello.app" method="GET">'
>     print >> RES, 'What is your name?'
>     print >> RES, '<input type="text" name="name" value="">'
>     print >> RES, '<input type="submit">'
>     print >> RES, '</form>'
> ###
>
> * Yuck!
>
> There's nothing wrong with that code, but it sure isn't pretty.  If
> you wanted to make the form look nicer, you'd have to add a whole lot
> more of those "print >> RES" lines, and that would get old real fast.
> Worse, it's hard to read and hard to maintain.
>
> In the next lesson, we'll look at a way of solving these problems by
> separating the logic of an app from its presentation.
>
>
> -----
>
> (c)2002 sabren enterprises inc
> feel free to forward this to a friend!
>
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>
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