http://www.perlmonks.org?node_id=1117789


in reply to Re^6: Removing AUTOLOAD from CGI.pm (flexibility?)
in thread Removing AUTOLOAD from CGI.pm

You had to use :any to get this behaviour: 

$ pmvers CGI
3.59
$ perl -E 'use CGI qw/:any/; say CGI->new->wibble({foo=>"bar"},"baz")'
<wibble foo="bar">baz</wibble>

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Re^8: Removing AUTOLOAD from CGI.pm (updated)
by LanX (Saint) on Feb 25, 2015 at 14:31 UTC
    > You had to use :any to get this behaviour:

    Didn't see this, because :any is not documented in CGI , though -any is as a "pragma" (and mentioned in your blog-post)

    There is also a mention of -compile , which means AUTOLOAD isn't needed to create the HTML-DSL.

    IOW you could¹ get rid of AUTOLOAD without deprecating HTML-subs, just by making -compile the default.

    But if you meant to deprecate the -autoload pragma, this seems to be a good idea.

    Installing an AUTOLOAD into the importing namespace sounds like a very hazardous hack.

    Cheers Rolf
    (addicted to the Perl Programming Language and ☆☆☆☆ :)

    PS: Je suis Charlie!

    ¹) I don't say "should" :)

    update

    After reading your blog-post again (>4th time) I'm puzzled. You only say you are disabling AUTOLOAD but not that you are deprecating precompiled HTML-subs in general.

    Did I misunderstand you? Maybe you could clarify.

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      > After reading your blog-post again (>4th time) I'm puzzled. You only say you are disabling AUTOLOAD but not that you are deprecating precompiled HTML-subs in general. Did I misunderstand you? Maybe you could clarify.

      That's correct. AUTOLOAD is gone but the HTML generation functions remain. I had to add/tweak the code to generate the HTML functions. It cleans up the code hugely.

      Here's the relevant commit. It's rather large so github doesn't show the full delta. There are a few other related commits later on, they all have #162 in the commit message.

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        > doesn't show the full delta

        True!

        I'm not fully comfortable with github yet, but I hope that's the code in question.

        Allow me some suggestions:

        start up time
        foreach my $tag ( _all_html_tags() ) {
    eval "sub $tag {
        return _tag_func(\$tag,\@_);
    }";
...
# again for end and start tags

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        This loop calls eval about 300 times, you can avoid this with installing this simple closure into your symbol table. 

        foreach my $tag ( _all_html_tags() ) {
    *$tag = sub { return _tag_func($tag,@_); }
...

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        As you can see in ... (closure vs eval) tag install time will improve with a factor >5-20 and you get rid of silly escaping.

        NB: I've tested on a netbook this should pretty much reflect old HW.

        lost features

        _all_html_tags() seems to be static, hence you are also deprecating the possibility to import new tags on demand like the <wibble> you mentioned.

        deprecation warning for -compile

        actually you are not deprecating -compile but making it the default now. So any legacy code using -compile should be fine.

        Not sure if you need to fill the logs then.

        killing AUTOLOAD

        I have the impression your main problem with AUTOLOAD was the maintenance of the ugly code-template to be evaled.

        If you switch to installing closures this problem disappears. ³

        killing CGI::Pretty

        IMHO CGI::Pretty should be able to easily survive now by monkeypatching _tag_func($tag,@_) instead of _make_tag_func() (AFAIS).

        Again no eval needed then.

        I understand that you are not interested, but maybe others like Your Mother want to contribute.

        best way for evaled code templates

        I agree that the currently evaled template in CGI::Pretty is a horrible mess because of all the escaped sigils.

        If you want/need to continue evaling code you might want to have another look at my sprintf approach in ... (closure vs eval).²

        Placeholders are simply marked with %1$s (1 = first arg) in a single quoted string (no escaping for $ or @ sigils needed, only % needs to be duplicated to %% )¹

        Hope this helps!

        :)

        Cheers Rolf
        (addicted to the Perl Programming Language and ☆☆☆☆ :)

        PS: Je suis Charlie!

        ¹) Otherwise regexing the placeholders is very stable with something like

          DB<106> $tmpl = '$#abc#=15' 
 => "\$#abc#=15"

  DB<107> $placeholder{abc}='str'
 => "str"

  DB<108> $tmpl =~ s/#(\w+)#/$placeholder{$1}/g
 => 1

  DB<109> $tmpl
 => "\$str=15"

  DB<110> eval $tmpl
 => 15

  DB<111> $str
 => 15

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        The need to escape #(\w+)# should be miniscule. (YMMV, but you are free to switch syntax, like {{(\w+)}} :)

        ²) in short

            eval sprintf <<'__CODE__', $tag;
        sub %1$s {
            "<%1$s>",@_,"</%1$s>";
        }
__CODE__

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        ³) maybe one day you'll decide it's easier to maintain AUTOLOAD for the -any and -autoload edge cases than to keep discussing with angry users? :)

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