Migrating to v0.3

v0.3.0 completes the transition from Symbol-based APIs to fully typed dispatch. Most migrations are mechanical find-and-replace operations — all breaking changes produce compile-time errors, so your test suite will catch everything.

Factory Functions

v0.3 introduces Search(), Extrap(), and Side() factory functions as the recommended high-level API. These are shorter to type and easier to discover than the concrete types. See Factory Functions for details.

Quick Search-Replace Reference

Run these replacements across your codebase. Order matters for partial-match safety.

Extrapolation (Symbols → Types)

v0.2 (removed)	v0.3 (factory)	v0.3 (direct type)
`extrap=:none`	`extrap=Extrap(:none)`	`extrap=NoExtrap()`
`extrap=:constant`	`extrap=Extrap(:constant)`	`extrap=ConstExtrap()`
`extrap=:extension`	`extrap=Extrap(:extend)`	`extrap=ExtendExtrap()`
`extrap=:wrap`	`extrap=Extrap(:wrap)`	`extrap=WrapExtrap()`

Note

The old symbol was :extension (with -ion); the new factory symbol is :extend (shorter, matches the type name better).

Also removed: ParabolaFit() → use QuadraticFit().

Side Selection (Symbols → Types)

v0.2 (removed)	v0.3 (factory)	v0.3 (direct type)
`side=:nearest`	`side=Side(:nearest)`	`side=NearestSide()`
`side=:left`	`side=Side(:left)`	`side=LeftSide()`
`side=:right`	`side=Side(:right)`	`side=RightSide()`

Derivatives (Int/Val → DerivOp)

v0.2 (removed)	v0.3
`deriv=0`	`deriv=DerivOp(0)` or `EvalValue()`
`deriv=1`	`deriv=DerivOp(1)` or `EvalDeriv1()`
`deriv=2`	`deriv=DerivOp(2)` or `EvalDeriv2()`
`deriv=3`	`deriv=DerivOp(3)` or `EvalDeriv3()`
`deriv=Val(n)`	`deriv=DerivOp(n)`
`deriv=(1, 0)`	`deriv=DerivOp(1, 0)`
`deriv=Val((1, 0))`	`deriv=DerivOp(1, 0)`

The old alias names (EvalValue, EvalDeriv1, EvalDeriv2, EvalDeriv3) remain exported and work unchanged.

Boundary Conditions (Renames)

v0.2 (removed)	v0.3
`NaturalBC()`	`ZeroCurvBC()` — S''=0 at boundaries
`ClampedBC()`	`ZeroSlopeBC()` — S'=0 at boundaries

Default BC changed: cubic_interp(x, y) now uses CubicFit() (was ZeroCurvBC()). To preserve the old behavior:

itp = cubic_interp(x, y; bc=ZeroCurvBC())  # explicitly specify old default

CubicFit minimum grid size

CubicFit() requires ≥ 4 grid points. For 3-point grids, use bc=ZeroCurvBC().

Search Policies (Renames)

v0.2 (removed)	v0.3 (factory)	v0.3 (direct type)
`Binary()`	`Search(:binary)`	`BinarySearch()`
`Linear()`	`Search(:linear)`	`LinearSearch()` ⚠️
`LinearBinary()`	`Search(:linear_binary)`	`LinearBinarySearch()`
`LinearBinary{4}()`	`Search(:linear_binary; linear_window=4)`	`LinearBinarySearch{4}()`
`HintedBinary()`	—	`LinearBinarySearch(linear_window=0)`

Recommended: just use the default

In v0.3, AutoSearch() is the default for all interpolants and adapts automatically. If you were using Linear() / LinearBinary() in v0.2, consider removing the explicit search policy entirely and relying on AutoSearch() + hint=Ref(1) for sequential patterns. See Search & Hints.

LinearSearch() is no longer recommended

The old Linear() (now LinearSearch()) has no binary fallback and degrades to O(n) for distant queries. Use LinearBinarySearch() or AutoSearch() (default) instead — they provide the same O(1) performance for monotonic data with a safe O(log n) fallback.

Behavioral Changes (Non-Breaking)

Default Search Policy: AutoSearch

The default search policy changed from BinarySearch() to AutoSearch(). Existing code compiles without changes, but runtime behavior differs for vector queries:

Query Type	v0.2 Default	v0.3 Default	Effect
Scalar	`BinarySearch()`	`BinarySearch()` (via AutoSearch)	No change
Sorted vector	`BinarySearch()`	`LinearBinarySearch()` (via AutoSearch)	Faster (up to ~5×)
Random vector	`BinarySearch()`	`LinearBinarySearch()` (via AutoSearch)	Slower (~2–3×)

If you have random vector queries and observe slowdowns, restore v0.2 behavior explicitly:

itp = cubic_interp(x, y; search=Search(:binary))
# or
itp = cubic_interp(x, y; search=BinarySearch())

Detailed Examples

Extrapolation

# ─── v0.2 (removed) ──────────────────────────────
cubic_interp(x, y, xq; extrap=:constant)
linear_interp(x, y, xq; extrap=:extension)

# ─── v0.3 (recommended: factory) ─────────────────
cubic_interp(x, y, xq; extrap=Extrap(:constant))
linear_interp(x, y, xq; extrap=Extrap(:extend))

# ─── v0.3 (alternative: direct type) ─────────────
cubic_interp(x, y, xq; extrap=ConstExtrap())
linear_interp(x, y, xq; extrap=ExtendExtrap())

# ─── ND per-axis (new variadic form) ─────────────
cubic_interp((x, y, z), data; extrap=Extrap(:extend, :constant, :none))

Side Selection

# ─── v0.2 (removed) ──────────────────────────────
constant_interp(x, y, xq; side=:left)

# ─── v0.3 ────────────────────────────────────────
constant_interp(x, y, xq; side=Side(:left))
constant_interp(x, y, xq; side=LeftSide())

# ─── ND per-axis ─────────────────────────────────
constant_interp((x, y), data; side=Side(:left, :nearest))

Derivatives

# ─── v0.2 (removed) ──────────────────────────────
cubic_interp(x, y, xq; deriv=1)
itp(q; deriv=Val((1, 0)))

# ─── v0.3 ────────────────────────────────────────
cubic_interp(x, y, xq; deriv=DerivOp(1))
itp(q; deriv=DerivOp(1, 0))

Boundary Conditions

# ─── v0.2 (removed) ──────────────────────────────
cubic_interp(x, y; bc=NaturalBC())
cubic_interp(x, y; bc=ClampedBC())

# ─── v0.3 ────────────────────────────────────────
cubic_interp(x, y; bc=ZeroCurvBC())    # S''=0
cubic_interp(x, y; bc=ZeroSlopeBC())   # S'=0

Search Policies

# ─── v0.2 (removed) ──────────────────────────────
linear_interp(x, y, xq; search=Binary())
linear_interp(x, y, xq; search=LinearBinary())

# ─── v0.3 (recommended: just use the default) ────
linear_interp(x, y, xq)                    # AutoSearch() adapts automatically

# ─── v0.3 (explicit override, if needed) ─────────
linear_interp(x, y, xq; search=Search(:binary))
linear_interp(x, y, xq; search=Search(:linear_binary))

# ─── v0.3 (alternative: direct type) ─────────────
linear_interp(x, y, xq; search=BinarySearch())
linear_interp(x, y, xq; search=LinearBinarySearch())

# ─── ND per-axis ─────────────────────────────────
cubic_interp((x, y, z), data; search=Search(:binary, :linear_binary, :auto))

Error Messages

v0.3 produces clear errors for old API usage:

julia> cubic_interp(x, y; extrap=:constant)
ERROR: MethodError: no method matching ...
# → Use Extrap(:constant) or ConstExtrap()

julia> cubic_interp(x, y, xq; deriv=1)
ERROR: TypeError: ...
# → Use DerivOp(1) or EvalDeriv1()

julia> linear_interp(x, y, xq; search=Binary())
ERROR: UndefVarError: `Binary` not defined
# → Use Search(:binary) or BinarySearch()

julia> Search(:bianry)
ERROR: ArgumentError: unknown search policy :bianry;
       valid options are :auto, :binary, :linear, :linear_binary
# → Factory functions show valid options on typos

Migration Checklist

Update extrap kwargs — replace :symbol with Extrap(:symbol) or typed constructors
Update side kwargs — replace :symbol with Side(:symbol) or typed constructors
Update deriv kwargs — replace Int/Val with DerivOp(n)
Update BC types — NaturalBC → ZeroCurvBC, ClampedBC → ZeroSlopeBC
Update search types — Binary → BinarySearch, etc.
Check default BC — if you relied on the implicit ZeroCurvBC default, specify it explicitly
Check search policy usage — AutoSearch() is now the recommended default; if you were using Linear(), switch to AutoSearch() + hint=Ref(1) (see Search & Hints)
Run tests — all changes produce compile-time errors, so tests catch everything