Struct MidFn 

pub struct MidFn;

Trait Implementations

impl Debug for MidFn

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Function for MidFn

Returns a substring starting at a 1-based position.

Remarks

• start_num is 1-based; values below 1 return #VALUE!.
• num_chars must be non-negative; negatives return #VALUE!.
• If start is beyond the end of the text, returns an empty string.
• Non-text inputs are coerced to text.

Examples

title: "Extract middle segment"
formula: '=MID("spreadsheet", 3, 5)'
expected: "reads"

title: "Start past end returns empty"
formula: '=MID("abc", 10, 2)'
expected: ""

related:
  - LEFT
  - RIGHT
  - REPLACE
faq:
  - q: "How does MID handle out-of-range start positions?"
    a: "If start_num is beyond the text length, MID returns an empty string."

[formualizer-docgen:schema:start] Name: MID Type: MidFn Min args: 3 Max args: 1 Variadic: false Signature: MID(arg1: any@scalar) Arg schema: arg1{kinds=any,required=true,shape=scalar,by_ref=false,coercion=None,max=None,repeating=None,default=false} Caps: PURE [formualizer-docgen:schema:end]

fn caps(&self) -> FnCaps

Capability flags for this function

fn name(&self) -> &'static str

fn min_args(&self) -> usize

fn arg_schema(&self) -> &'static [ArgSchema]

fn eval<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], _: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

The unified evaluation path.

fn namespace(&self) -> &'static str

fn variadic(&self) -> bool

fn volatile(&self) -> bool

fn aliases(&self) -> &'static [&'static str]

Optional list of additional alias names (case-insensitive) that should resolve to this function. Default: empty slice. Implementors can override to expose legacy names. Returned slice must have ’static lifetime (typically a static array reference).

fn function_salt(&self) -> u64

fn eval_reference<'a, 'b, 'c>( &self, _args: &'c [ArgumentHandle<'a, 'b>], _ctx: &dyn FunctionContext<'b>, ) -> Option<Result<ReferenceType, ExcelError>>

Optional reference result path. Only called by the interpreter/engine when the callsite expects a reference (e.g., range combinators, by-ref argument positions, or spill sources).

fn dispatch<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], ctx: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

Dispatch to the unified evaluation path with automatic argument validation.