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encode

# $EPIC: encode.txt,v 1.4 2009/06/01 00:47:41 jnelson Exp $

Synopsis:

$encode(<text>)

Technical:

If the <text> argument is omitted the empty string is returned.

The output of this function is a transformation of <text> that has the following characteristics AND ONLY the following characteristics:

Characteristic Example
It is unique encode(X) != encode(Y) for all X != Y
It is case sensitive: encode(foo) != encode(FOO)
It is reversable: decode($encode(foo)) == [foo]
It creates an lval: @ encode(foo) = [bar]

This particular implementation breaks each octet in <text> into two four bit nybbles and adds the nybble to 0x41. The return value is therefore twice the length of the input <text>. THIS IS SUBJECT TO CHANGE IN THE FUTURE.

Hardcoding $encode()d values into your script IS A BAD THING. Please be aware that $encode() may change in the future and your script will break and IT WON'T BE MY FAULT.

Practical:

It is common practice to use associative arrays to store information about servers, channels, and nicknames. Consider if you wanted to be able to store the userhost of every user on every channel you are on. You might want to organize it like:

BAD:   /assign uh[<server>][<channel>][<nick>] <userhost>

Unfortunately, <server>, <channel>, and <nick> might contain characters that are not valid characters in a variable name. If you tried to do it, you would get the error “ASSIGN names may not contain ….”

The $encode() function converts any arbitrary string of text into a string that can be used as part of a variable name:

GOOD:  /assign uh[$encode(<server>)][$encode(<channel>)] [$encode($<nick>)] <userhost>

Then you can use /FOREACH to iterate over the sub-arrays:

/assign array uh[$encode(<server>)][$encode(<channel>)]
/foreach $array x {
  echo $array.$x
}

Returns:

A string that is deterministically based on <input>

Examples:

$encode(hello there)               returns "GIGFGMGMGPCAHEGIGFHCGF"
$decode(GIGFGMGMGPCAHEGIGFHCGF)    returns "hello there"
$decode($encode(hello there))      returns "hello there"

History

This function first appeared in ircII-2.2pre8.

encode.txt · Last modified: 2016/08/02 22:21 by sgrubnick