hasarg()

hasarg()

hasarg(<name>[, <scope>])

hasarg() returns 1 if the attribute running now has an argument called <name>, even when its value is empty or 0, and 0 if not. A number names an argument by position: hasarg(0) is %0. Case does not matter. Outside an attribute, hasarg() returns 0.

<scope> is one of:

• visible, the default: any argument the attribute can read. That includes what @include carried over from its caller, and the counts a function’s items... argument makes, such as itemscount.
• supplied: only what this call itself was passed. After @include/args, that is the arguments the include named, even one with the same value as the caller’s.

Any other <scope> returns #-1 INVALID ARGUMENT.

hasarg() never evaluates the argument. Each u() call has arguments of its own; a built-in function such as iter() keeps the ones around it, and a queued action keeps the ones it was queued with.

• hasarg examples: testing an argument, and what an included attribute sees

::: seealso

• named arguments
• uargs()
• @include :::

Examples

&SHOW me=[hasarg(who)]|[hasarg(who,supplied)]|[hasarg(0,supplied)]|[hasarg(missing)]
think uargs(me/SHOW,who,)

Output: 1|1|1|0

An included attribute sees its caller’s who, but only its own x is supplied:

&INNER me=think [hasarg(who)]/[hasarg(who,supplied)]/[hasarg(x,supplied)]
&OUTER me=@include/args me/INNER=x,1
@trigger/inline/args me/OUTER=who,Bob

Output: 1/0/1, after the trigger’s own line.