FmtParam

An unbound interpolation in a Fmt.

A FmtValue already carries a value. A FmtParam carries only a name and a specification. What the hole means is up to the consumer of the sequence — a SQL statement binds it as a placeholder, for example. Fmt.format fills holes from its arguments.

FmtParam exposes the same formatting fields and pad method as FmtSpec. Calling it with new keyword options returns a new FmtParam naming the same parameter.

Constructor

`FmtParam name …`

Parameters

Name	Type	Description
`name`	`(Int \| Sym)`
`:fill?`	`FmtFill`
`:align?`	`FmtAlign`
`:sign?`	`FmtSign`
`:width?`	`Int`
`:precision?`	`Int`
`:alt?`	`Bool`
`:kind?`	`FmtKind`
`:source?`	`Str`	Interpolation as written in source

Errors

Exception	Condition
`TypeError`	`name` is neither an `Int` nor a `Sym`

Example

let hole = FmtParam :user: width: 8
assert_eq $hole.name :user:
assert_eq $hole.width 8

Methods

`(call) … -> FmtParam`

Returns a new FmtParam naming the same parameter with the supplied options merged. Positional arguments are not accepted. The result is synthetic rather than source-derived, so its source is nil.

Parameters

Name	Type	Description
`:fill?`	`(FmtFill \| nil)`	Padding fill
`:align?`	`(FmtAlign \| nil)`	Alignment
`:sign?`	`(FmtSign \| nil)`	Sign display
`:width?`	`(Int \| nil)`	Minimum width in grapheme clusters
`:precision?`	`(Int \| nil)`	Numeric precision or maximum graphemes
`:alt?`	`(Bool \| nil)`	Enables alternate formatting
`:kind?`	`(FmtKind \| nil)`	Representation kind

`(eq) other`

Two parameters are equal when they name the same parameter under the same specification and record the same source.

`name() -> (Int | Sym)`

The parameter named by this position, as an Int or a Sym.

`source() -> (Str | nil)`

The text the parameter was written as, or nil. A ${#...} in a t"..." records the whole interpolation, sigil and delimiters included.

let seq = t"a=${#0:>3}"
assert_eq $seq[1].source r"${#0:>3}"