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Re: Re: Perlmonk's "best pratices" in the real world

by schweini (Friar)
on Nov 13, 2003 at 16:20 UTC ( #306829=note: print w/replies, xml ) Need Help??


in reply to Re: Perlmonk's "best pratices" in the real world
in thread Perlmonk's "best pratices" in the real world

That BBX-code i mentioned works in the sense of being 'functional' - i.e. does what it's supposed to do, but impossible to expand. actually, for the last year, i've been replacing all of it with my perl-code, and this meditation was in part inspired by the fear that ina couple of years, some poor schmuck will have to look at my code the same dazzled way i've been looking at that BBX stuff.

re: CGI.pm
i've always used it in the 'old school' way of getting my params (via Vars()) with it, and then basically forgetting about it. i prefer using my own header-generators and HTML-printing subs.
re: strict/warning
i frankly tried it a couple of times, but got annoyed by the a bit over-pedantic messages makeing a big fuss about nothing too serious. but iread about 'no strict vars' somewhere, so i'll give that a shot...
re: placeholders
i've actually been advocating placeholders on the DBI-list and here (i think) a couple of times, because i am so in love with them (you can't imagine the effect that BBX code had on my mental health)
re: OO
agreed - i think OO is cool for complex modules (DBI, Tk, etc.), where inheritance and friends actually make sense - but my apps that simply use all that funcionality tend to be a lot cleaner without OO...
re: templates
for 'normal' websites i guess i'd agree, but right now i'm working on this intranet-thing, and since basically all content is generated by my html-creator-subs, and formatted on the fly according to the data, i doubt that they would help me a lot right now..
re: CGI::App
I still don't get that one..i use the good ol' if ($in{action} eq "foo") style, and simply refuse to believe that using subs instead of conditionals make that much of a difference...
re: PM-style
very cool theory why perlmonks code they way they seem to!

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Re: Re: Re: Perlmonk's "best pratices" in the real world
by hardburn (Abbot) on Nov 13, 2003 at 16:58 UTC

    . . . this meditation was in part inspired by the fear that ina couple of years, some poor schmuck will have to look at my code the same dazzled way i've been looking at that BBX stuff.

    Heh, I often wonder the same thing about my code. Often, I end up being that poor schmuck and end up cursing myself. Actually, I consider this a good thing--it means I learned something between then and now.

    i've always used it in the 'old school' way of getting my params (via Vars()) with it

    Nothing wrong with Vars()--it's just param() in disguise :) As long as you're not doing it by hand, you're OK.

    i prefer using my own header-generators and HTML-printing subs.

    Note that even in simple cases (outputing HTML, no cookies, etc.), CGI has already avoided problems for you:

    $ perl -e 'use CGI qw(:standard); print header();' Content-Type: text/html; charset=ISO-8859-1

    Notice the addition of charset. I don't remember the specifics, but that avoids a potential cross-site scripting vulnerability.

    Every time I thought I knew how to do CGIs safely, I find out about a new edge case that was already handled by CGI.pm, such as the above. Which is why I stick to it or one of its alternate cousins.

    As for HTML creator subs, I think the case would be much stronger for them if Perl lacked a good templating system. As it happens, Perl has a lot of good templating systems (too many, some might say). Even if your project doesn't have an HTML specialist, I find templates are often easier to work with than mucking with code.

    i frankly tried it a couple of times, but got annoyed by the a bit over-pedantic messages makeing a big fuss about nothing too serious.

    Other then strict 'refs' (and only in very specific situations, like automatic generation of accsessors/mutators with closures), I've never seen strict give an error that wasn't serious. Maybe the code appeared to work, but it could have caused problems that would only be caught once it hit production.

    As I noted, warnings is occasionally bothersome, but usually the same rules apply as for strict.

    I still don't get that one..i use the good ol' if ($in{action} eq "foo") style, and simply refuse to believe that using subs instead of conditionals make that much of a difference...

    I'm currently on a project that uses CGI::Application that as of this posting has 65 run modes, and will probably get a few more before it's done. The dispatch table that CGI::Application means that each run mode is called in O(1) time, instead of O(n) worst-case as it would be with a conditional tree. So it's more efficient, if nothing else.

    Further, I keep all the run modes in a hash at the top of the applications, which is much easier to read then a huge conditional tree. Thanks to etags, my editor can jump directly to any run mode with two key strokes with the cursur over the desired mode in that hash (which is really nice, since this module is over 3000 lines long).

    Lastly, CGI::Application has already done some things for me, such as loading HTML::Template files and doing the output to the browser.

    One thing I don't like about it is that you can't write to the browser on your own, but have to return the complete output at the end of the sub. This is a major problem for one part of my application, where reports are generated from a database. The reports could get quite large--larger than I'd want to load into memory at once if I could avoid it.

    ----
    I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
    -- Schemer

    : () { :|:& };:

    Note: All code is untested, unless otherwise stated

      One thing I don't like about it is that you can't write to the browser on your own, but have to return the complete output at the end of the sub. This is a major problem for one part of my application, where reports are generated from a database. The reports could get quite large--larger than I'd want to load into memory at once if I could avoid it.

      You can do something like this, if you want:

      sub mymode { #... print $self->_send_headers; # print your data; $self->teardown; exit( 0 ); }

      This is the method suggested on the CGI::App wiki to do an "early exit."

      --
      "To err is human, but to really foul things up you need a computer." --Paul Ehrlich

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