Build the Shared Coordinator for a Multi-Instance Embedding

Constructs a single pure, non-reactive coordinator object from the full set of plot formulas. The coordinator computes the cross-formula partition – a shared key used by exactly one formula renders in that formula's inline shared section; a key used by two or more formulas renders in the one standalone ptr_shared_panel(). Because every consumer derives its view from this one object, the UI and server can never disagree about the partition.

Usage

ptr_shared(
  formulas,
  id = NULL,
  ui_text = NULL,
  expr_check = TRUE,
  draw_all_label = "Draw all"
)

Arguments

formulas: A non-empty character vector or list, one element per embedded ptr_ui() instance. Each element is either a formula string or a quoted ggplot expression (rlang::expr(...) / quote(...)); quoted expressions are deparsed to their source string, and the two forms are interchangeable (mixed lists are allowed). A built ggplot object (e.g. g <- ggplot(...) + geom_point() then passing g) is not accepted – its source is unrecoverable, so quote it with expr() instead. Note: a native pipe |> inside a quoted expression is desugared by R's parser before capture, so it does not survive into the generated code panel (use %>% or a formula string to preserve it).
id: Optional character scalar that namespaces every id this coordinator emits, so two or more coordinators can coexist in one Shiny session without colliding on shared input slots. When non-NULL, every id (shared_<key>, shared_<key>_stage_enabled, ptr_shared_draw_all, ptr_shared_errors, the stage-block DOM id, and each consumer renderUI container) is prefixed <id>- using Shiny NS()'s separator. The default NULL preserves today's flat ids byte-for-byte – single-panel apps need no change. Must be NULL or a non-empty string matching ^[A-Za-z][A-Za-z0-9_]*$; ptr_shared_panel(), ptr_ui_shared_panel(), and ptr_shared_server() all read it off obj$id – their signatures do not change.
ui_text: Optional copy overrides forwarded to the auto-built widgets (see ptr_app()'s ui_text argument).
expr_check: Whether to validate ppExpr placeholders during formula translation. Default TRUE. Runtime-typed ppExpr input is always screened against the built-in denylist regardless.
draw_all_label: Label for the "Draw all" button rendered in the panel when two or more formulas are supplied.

Value

A ptr_shared_spec S3 object. Public fields: panel_keys (cross-formula keys), local_keys_by_formula (per-formula inline keys). Deterministic and idempotent for a given formulas.

Details

This is strictly multi-instance API: with a single ggpaintr instance all shared widgets auto-render inline and no coordinator is needed. The coordinator is consumed by exactly three functions, each taking only the object: ptr_shared_panel(), ptr_ui_shared_panel(), and ptr_shared_server().

Errors when no formula declares a shared = "..." annotation – building the coordinator is a declaration of intent.

Removed `shared_ui`

shared_ui (a named list of function(id) -> shiny.tag builders) is no longer supported. Its original intent was to let two placeholders that share a key share the same UI settings. But each placeholder already carries its own build_ui rule, and two shared= placeholders simply reuse that one rule when their widget collapses to the panel. The customisation therefore comes from the placeholder's build_ui (ptr_define_placeholder_*(build_ui = ...)), not from a separate shared_ui override — so the override was redundant, and for var consumers it actively dropped the formula default and froze the column list. To customise a shared widget, define a custom placeholder with the build_ui you want and use it in the formula. Label-only divergence for the shared widget still has its own channel (node$shared_label).

Examples

obj <- ptr_shared(c(
  "ggplot(mtcars, aes(x = ppVar(shared='x'), y = ppVar)) + geom_point()",
  "ggplot(mtcars, aes(x = ppVar(shared='x'), y = ppVar)) + geom_bar()"
))
obj$panel_keys   # "x" — shared by both formulas
#> [1] "x"

# Quoted expressions work too, and may be mixed with strings:
obj2 <- ptr_shared(list(
  rlang::expr(ggplot(mtcars, aes(x = ppVar(shared = "x"), y = mpg)) + geom_point()),
  "ggplot(mtcars, aes(x = ppVar(shared = 'x'), y = hp)) + geom_line()"
))
obj2$panel_keys  # "x"
#> [1] "x"