Skip to content

editor exception facts

Jump to bottom
Alexander Liberov edited this page Nov 13, 2026 · 1 revision

Exception facts in the editor

The index records every raise, re-raise and except handler with the exception type it names (exception-facts, since 1.46). Since 1.47 the editor shows that fact too, and an MCP client can ask for it. All three surfaces read through ONE reader (DRagLint.Query.ExceptionFacts, the same code as the exception-facts verb), so they cannot disagree with the CLI.

Hover: the Raises: line

Hovering a routine (LSP textDocument/hover, and draglint/hoverBundle, which the Delphi IDE popup uses) adds one line after the other analysis facts:

Raises: EFoo (bound), EArgumentException (spelled)

Each type is named once, in source order, with how it is known: bound (the index resolved the type), handler (a raise; / raise E inside on E: EFoo do), local (a local or parameter of that type), name (the one indexed type of that spelling), spelled (the source names it, the index does not hold it) or unknown (raise MakeError(..), a raise; under a bare except). A routine that raises nothing gets no line. What a routine CATCHES is the existing Catches: line (the same one document writes into the doc block).

Code lens

textDocument/codeLens adds a lens on the routine's declaration line, beside the caller count:

raises 2 types, handles 1 type

Distinct raised types and distinct handled types (a bare except counts as one); either half is left out when it is zero.

Since 1.49 the lens is clickable: its command is draglint.exceptionFacts with [uri, line] (workspace/executeCommand, advertised in executeCommandProvider). The server answers the routine's raise and handler sites, the same rows the title counts:

[{"uri": "file:///C:/p/uExc.pas", "line": 30, "character": 10, "action": "handles",
  "type": "EFoo", "via": "bound", "routine": "uExc.TWorker.Safe"}, ...]

(0-based positions; [] under --no-exception-facts or for a line with no such routine). The VS Code extension shows them in a quick pick (handles EFoo / line 31 (bound)); picking one jumps to the site.

The Delphi IDE lens reads draglint/callerCounts, not textDocument/codeLens, so since 1.49 that reply carries the same titles too: exceptions: [{"line": L, "title": "raises 2 types"}] beside counts and implementors (0-based declaration lines; [] when switched off; an older engine sends no exceptions key). The plugin renders it beside the caller count.

MCP: get_exception_facts

tools/call with name = get_exception_facts and exactly one of:

  • target: a routine, qualified or by its trailing part;
  • name: an exception type, bare or qualified (exact type, no ancestry);
  • db (optional): an index path when the server was started without one.

The reply is the JSON of drag-lint exception-facts --json, byte for byte. Neither or both selectors is an error.

Switching it off

ON by default (owner ruling, wave 148). drag-lint lsp --no-exception-facts removes the hover line, the lens and the callerCounts titles (draglint.exceptionFacts then answers []); hover is then byte-identical to 1.46. The MCP tool is always available (a new tool changes no existing answer).

Cost

The hover reads the routine's rows through the symbols indexes (one store open plus one indexed query; about 80 ms over a bare store open on the 520k-ref drag-lint index, measured min-of-10 on a loaded machine). The lens reads the file's rows once per codeLens request.

Limits

No escape analysis: the line lists the routine's OWN raise sites, not what its callees raise (that is ask exception-paths). On an index written before 1.46 the types read unknown.

Clone this wiki locally