Additional variable

This is a fully working prototype with just few lines of code and I think it would fit nicely in bot_factoid.module:

http://drupal.pastebin.com/HYw19fCZ

Before submitting a patch, can you please test it and tell me your opinion on this?

Here, you can try it online: http://jazzit.hr/test/index.php

The "ask?" factoid will work independently as it already works right now. Take a look at these examples:

EXAMPLE 1:
=======
factoid: ask
statement: Hello world!
command: ask is <reply>Hello world!

usage: ask | madjoe
Bot output: Hello world!

EXAMPLE 2:
=======
factoid: ask
statement: Hello world, said $1!
command: ask is <reply>Hello world, said $1!

usage: ask | madjoe
Bot output: Hello world, said madjoe!

EXAMPLE 3:
=======
factoid: ask
statement: Hello world, said $1 $3$2!
command: ask is <reply>Hello world, said $1 $3$2!

usage: ask |
Bot output: Hello world, said !

EXAMPLE 4:
=======
factoid: ask
statement: Hello world, said $1, $3!
command: ask is <reply>Hello world, said $1, $3!

usage: ask | madjoe | morbus | beanluc ||
Bot output: Hello world, said madjoe, beanluc!

EXAMPLE 5:
=======
factoid: ask
statement: Hello world, said $1!
command: ask is <reply>Hello world, said $1!

usage: ask
Bot output: *NOTHING*

EXAMPLE 6:
=======
factoid: ask
statement: Hello world, said $1!
command: ask is <reply>Hello world, said $1!

usage: ask?
Bot output: THE SAME AS #3: Hello world, said !

The usage for the last example (#6) is not implemented in this script, since that piece of code is already included in Bot module.

This small script could already work for any existing factoid that doesn't have placeholders defined at all.

Slightly updated dev-version of the same code: http://drupal.pastebin.com/KVw3LkJR

Since I've already mentioned a bot from #ubuntu, here's the description: http://ubottu.com/devel/wiki/Plugins
Ubottu factoids: http://ubottu.com/factoids.cgi

I'd like to study their usecase before I start working on that patch. All suggestions are welcome.

@Morbus: Maybe we do something like "!1|you" in the factoid itself, to specify a default value?

Actually I love this idea. To be sure I understood you correctly, can you please give me an example of it?

Great! That is exactly what I had on mind... I love the idea... I will work on that to update the current code.
I also thought of implementing something else: should we include some simple predefined commands as a user's input?

For this example I'll try to use a slightly complicated usecase:

> BOTNAME: support is Hello !(1|user) Have a cup of !(2). Go here: http://lmgtfy.com/q=!url(3)

> support || stfu | bot module site:drupal
> Hello user! Have a cup of stfu. Go here: http://lmgtfy.com/q=bot+module+site%3Adrupal

Notes:

1. !2 should be equal to: !(2) and !(2|)

2. Syntax: ![1-9] or !([1-9]|optional default value) or !COMMAND(Text goes here) or !COMMAND([1-9]|optional default value)

Besides !url() that could engage urlencode(), is there any other need for a predefined command from that perspective?

I've made the syntax exactly like I described in my previous comment. Currently available commands: !url() and !enc() - case insensitive.

URL: - stands for urlencode()
ENC: - stands for str_rot13()

Do you have any other idea to expand the list of commands with useful features?

Demo: http://jazzit.hr/test/index.php

P.S. I didn't apply the automata theory, so you won't be able to use nested commands, but I don't see it as an issue here.

TODO: Allow some spacing between elements for easier reading.

1. Do you think you can handle default value without a regex pattern?
2. Regex is more powerful than strtr() and just because of possible usage of commands I suggested two syntaxes: for simple variables "!2" and commands with variables - expressions "!(2) and "!(2|)" represent those variables as "empty" commands - a better example of a command would be "!command(2|default)". If we get rid of commands, then it's ok, we can accept just that primitive option as a single syntax.
3. BTW, my both syntaxes are held by a single regular expression.
4. Why are you so adverse to having commands in syntax? I find it quite handy to use it for urlencode() like in this example:

BOTNAME: find is <reply>!1: Go here: http://drupal.org/search/apachesolr_search/!URL(2|how to contribute Drupal)?filters=type:!(3|book)

find | zed | views 2 theming

zed: Go here: http://drupal.org/search/apachesolr_search/views+2+theming?filters=type:...