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PLP-3.25
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/ PLP::Functions

NAME

PLP::Functions - Functions that are available in PLP documents

DESCRIPTION

The functions are exported into the PLP::Script package that is used by PLP documents. Although uppercased letters are unusual in Perl, they were chosen to stand out.

Most of these functions are context-hybird. Before using them, one should know about contexts in Perl. The three major contexts are: void, scalar and list context. You'll find more about context in perlfunc.

Some context examples:

    print foo();  # foo is in list context (print LIST)
    foo();        # foo is in void context
    $bar = foo(); # foo is in scalar context
    @bar = foo(); # foo is in list context
    length foo(); # foo is in scalar context (length EXPR)

The functions

Include FILENAME

Executes another PLP file, that will be parsed (i.e. code must be in <: :>). As with Perl's do, the file is evaluated in its own lexical file scope, so lexical variables (my variables) are not shared. PLP's <(filename)> includes at compile-time, is faster and is doesn't create a lexical scope (it shares lexical variables).

Include can be used recursively, and there is no depth limit:

    <!-- This is crash.plp -->
    <:
        include 'crash.plp';
        # This example will loop forever,
        # and dies with an out of memory error.
        # Do not try this at home.
    :>
include FILENAME

An alias for Include.

PLP_END BLOCK

Adds a piece of code that is executed when at the end of the PLP document. This is useful when creating a template file:

    <html><body>       <!-- this is template.plp -->
    <: PLP_END { :>
    </body></html>
    <: } :>

    <(template.plp)>   <!-- this is index.plp -->
    Hello, world!

You should use this function instead of Perl's built-in END blocks, because those do not work properly with mod_perl.

EscapeHTML STRING

Replaces HTML syntax characters by HTML entities, so the text can be output safely. You should always use this when displaying user input (or database output), to avoid cross-site-scripting vurnerabilities.

In void context, changes the value of the given variable.

    <: EscapeHTML($user_input); print "<pre>$user_input</pre>"; :>

In other contexts, returns the changed version.

    <a href="<:= EscapeHTML($ENV{REQUEST_URI}) :>">

Be warned that single quotes are not substituted, so always use double quotes for attributes. Also does not convert whitespace for formatted output; use Entity() for that.

To escape high-bit characters as well, refer to HTML::Entities.

Entity LIST

Formats given arguments for literal display in HTML documents. Similar to EscapeHTML(), but also preserves newlines and consecutive spaces using corresponding <br> and &nbsp; respectively.

In void context, changes the values of the given variables. In other contexts, returns the changed versions.

    <: print '<p>' . Entity($user_input) . '</p>'; :>

Inside attributes, always use EscapeHTML() instead.

EncodeURI LIST

Encodes URI strings according to RFC 3986. All disallowed characters are replaced by their %-encoded values.

In void context, changes the values of the given variables. In other contexts, returns the changed versions.

    <a href="/foo.plp?name=<:= EncodeURI($name) :>">Link</a>

Note that the following reserved characters are not percent-encoded, even though they may have a special meaning in URIs:

        / ? : @ $

This should be safe for escaping query values (as in the example above), but otherwise it may be a better idea to use URI::Escape instead.

DecodeURI LIST

Decodes %-encoded strings. Unlike URI::Escape, it also translates + characters to spaces (as browsers use those).

In void context, changes the values of the given variables. In other contexts, returns the changed versions.

ReadFile FILENAME

Returns the contents of FILENAME in one large string. Returns undef on failure.

WriteFile FILENAME, STRING

Writes STRING to FILENAME (overwrites FILENAME if it already exists). Returns true on success, false on failure.

Counter FILENAME

Increases the contents of FILENAME by one and returns the new value. Returns undef on failure. Fails silently.

    You are visitor number <:= Counter('counter.txt') :>.
AutoURL STRING

Replaces URLs (actually, replace things that look like URLs) by links.

In void context, changes the value of the given variable. In other contexts, returns the changed version.

    <: print AutoURL(Entity($user_input)); :>
AddCookie STRING

Adds a Set-Cookie header. STRING must be a valid Set-Cookie header value.

AUTHOR

Juerd Waalboer <juerd@cpan.org>

Current maintainer: Mischa POSLAWSKY <shiar@cpan.org>