[Gllug] question about python/perl

[salsaman at xs4all.nl]

On Thu, February 24, 2011 16:27, Joel Bernstein wrote:
> On 24 February 2011 16:11, Martin <mherda at gmail.com> wrote:
>> Thanks for the clarification on frameworks. It's still somewhat
>> confusing. I
>> guess I'd have to try one to be completely
>> clear on that.
>> I'm a newbie web designer. The few websites I've done are quite simple.
>> I
>> code them in emacs (html+css+jquery).
>> I haven't used much php yet. If I do, it's for very simple tasks, eg.
>> including the header/footer in all pages, etc.
>> So to get a few things straight regarding frameworks:
>>
>> 1. I'd still code html+css+jquery in an editor by hand or do they have a
>> template system like CMSs (joomla, drupal) have. (I am aware that CMS
>> templates need to be coded first as well.)
>
> The templating system is a wrapper on top of the HTML/CSS that renders
> out valid HTML/CSS.
> Imagine, for example, a page that displays a set of values from a
> database. Assuming a suitable resultset has already been prepared by a
> controller, your template can do something like (super-simple
> contrived example).
>
> <table>
> <th><td>User</td><td>Last logged in date</td></th>
> [% FOREACH user IN users %]
> <tr><td>[% user.name %]</td><td>[% user.lastlogin %]</td></tr>
> [% END %]
> </table>
>
> This is the basis of any dynamic server-side templating system, like
> PHP or whatever.
>
>> 2. If eg. it's a python framework (eg. django), do I need to know python
>> or
>> is it similar to a CMS that you don't need to know the language it's
>> written
>> in to use it)
>> Here I'm probably confusing a CMS with a web framework.
>
> Yes, you need to know Python / Perl / whatever since your controller
> actions will be written in that language.
>
>> 3. My understanding is that web frameworks are more for web
>> applications,
>> less for web design (html+css+jquery). I'm confused as to the
>> nomenclature,
>> what is a 'web application' ? Can you give me an example of a web
>> application? I guess coding some slides or navigation menu in jquery
>> can't
>> be called a web application. It's mostly concerned with the website's
>> looks.
>
> Yes, precisely. The web application is the software that runs the
> backend for your website - it processes form submissions, handles user
> authentication, mediates access to databases and so on.
>
>> 4. I haven't had the need to deal with databases yet or anything more
>> complex. Does that mean that a web framework
>> would not come handy here? I mean you pointed out some advantages of
>> using
>> webframeworks and I'd like to use them, but at this stage wouldn't it be
>> an
>> overkill?
>
> It would be overkill to use a web framework for things you can do
> entirely on the client side, but how many websites today really have
> no dynamic server-side component? For example, every AJAX request you
> make from jQuery has to return data from somewhere.
>
> You can think of web frameworks as glorified dispatchers. That is, if
> you make a request like GET /users/joel/flowers/rose/petals/, it
> handles unpacking that URI path and calling the appropriate controller
> actions. Clever dispatchers like that in Catalyst allow different,
> orthogonal pieces of code to handle different parts of that URI. For
> example, you might have one action that deals with /users/<user name>,
> captures that username, looks up the user object and stashes it for
> further actions to use. You'd then have another for flowers/<flower
> name> which looks up the flower by name, stashes the flower object.
> Then the petals action does whatever it does (e.g. grab the number of
> petals from the stored rose object and stick it into the stash for a
> template to render a nice page). As Simon said earlier, it's about
> separating different functions from each other, factoring your code in
> such a way as to make it sensible, maintainable, reusable and
> reflecting the domain it models.
>
> /joel
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>

Quite right, although in my experience it is far more common to use a
query string rather than the address to hold parameters, for example:

http://www.example.com?name=joel&flower=rose&type=petal

A smart enough framework would then create a parameter called "name" and
assign it the value "joel", create a variable "flower" with value "rose"
and a variable "type" with value "petal". These variables are then used in
the code which returns html to the client.


Salsaman.






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