ischannel function

Synopsis

$ischannel(<channel name>)

Technical

Tests whether the first character of the supplied name is a recognized channel prefix. It uses the current server context's cached 005 CHANTYPES value when nonempty; otherwise it falls back to +, #, &, and !. There is no separate server-selector argument.

Only the prefix is tested. This does not validate the rest of the name, require a character after the prefix, check whether the channel exists, or check whether you have joined it. It sends no server query. A name such as # can return one even though the server may reject it as a join target.

The name is the first function argument word; additional words are ignored. Quote-aware parsing follows /xdebug dword. Missing input returns empty. An explicitly empty name, when parsed as one argument, returns zero.

Practical

Scripts can use this to add a default # prefix when the user enters a bare channel name:

alias join (channel, ...) {
    if (ischannel($channel)) {
        //join $channel $*
    } else {
        //join #$channel $*
    }
}

The doubled slash invokes the built-in join rather than this alias. This is a convenience for a server supporting # channels, not complete channel-name validation.

Returns

1 for a recognized leading prefix, otherwise 0. Missing the required argument returns empty. No diagnostic is printed.

Examples

With the fallback prefix set, $ischannel(#blah) and $ischannel(&blah) return 1, while $ischannel(blah) returns 0. A server advertising a different nonempty CHANTYPES set can change these results.

History

First appeared in ircII-2.2pre1.

Source

Registration and first-word parsing: source/functions.c. is_channel() prefix test and fallback: source/parse.c. Cached 005 settings: source/server.c.