Table of Contents
Argument Lists
Argument lists are an optional way to automatically shift values from $* into local variables. You can use argument lists in your aliases or your ons. The fix_arglist function also handles arglists.
Behavior of Argument Lists
When an alias or on is called, the magic variable $* is set with the arguments passed into your code. Usually the first thing most people do is copy arguments from $* into local variables, such as:
alias oofda {
local var1 $0;
local var2 $1;
local var3 $2-;
echo $var1 and $var2 and $var3!;
};
But wouldn't it be easier if you could just have the client automatically assign the values for you? Argument lists are how you do this
alias oofda (var1, var2, var3) {
echo $var1 and $var2 and $var3!;
};
or for ons,
on ^join * (nick, chan, userhost, extra) {
xecho -b $nick!$userhost has joined $chan $extra;
};
Ordinarily, the whole of $* is put into the arguments; anything left in $* is put into the final variable. Thus, $* is usually the empty string in an alias or on that uses argument lists. You can overrule this.
Syntax of Argument Lists
An argument list is a comma separated list of terms, surrounded in parenthesis. Each term should be a variable, with an optional number of words specification, with an optional default value. The final term must be either a regular variable term, or the literal string “void”, or the literal string “…”.
| Syntax | Meaning |
|---|---|
| varname | Assign the next word to $varname |
| varname words N | Assign the next N words to $varname |
| varname uwords N | Assign the next N uwords to $varname |
| varname qwords N | Assign the next N qwords to $varname |
| varname dwords N | Assign the next N dwords to $varname |
| varname default “val” | Assign the next word to $varname, but use the value val if an argument wasn't provided. |
| … | (Final argument only) The remainder of the arguments (if any) should be assigned to the $* magic expando. |
| void | (Final argument only) The remainder of the arguments (if any) should be discarded. |
- The default word-specification is “words 1”
- The default default-value is the empty string (“”)
- If you don't provide any argument list, (…) is the default.
| Word Type | Definition |
|---|---|
| words | |
| uwords | |
| qwords | |
| dwords |
Semantics of Argument Lists
When you call an alias that has an argument list, each term of the argument list is created as a local variable, and its initial value is set to $0 (or however many words you specified), and those word(s) are removed from $*.
If $* runs out before the argument list does, then any remaining arguments receive their default values (including the default-default value of “”)
The last argument in the list is either a variable, the literal string '…', or the literal string 'void'. The remainder of $* is either moved to the variable, kept in $*, or discarded entirely, respectively.
Naturally, argument lists change $*, and there is no way to recover the original value of $* in an alias (or on) that uses arglists.