traceback

Documentation

Overview

Package traceback ports cpython/Python/traceback.c. v0.3 ships the data shape, the format/print entry points, and a minimal frameless builder used by the errors package to attach traceback rows from Go call sites. Real frames join in v0.6 once the VM lands.

Index

• Variables
• func Format(tb *Traceback) string
• func FormatException(tb *Traceback, typeName, message string) string
• type Entry
• type Traceback
  • func New(entry Entry) *Traceback
  • func Push(tb *Traceback, entry Entry) *Traceback

Variables

var Type *objects.Type

Type is the type singleton for the `traceback` builtin type.

CPython: Python/traceback.c:269 PyTraceBack_Type

Functions

func Format

func Format(tb *Traceback) string

Format returns the multi-line traceback string, oldest entry first. Mirrors traceback.format_tb output.

CPython: Python/traceback.c:L985 _PyTraceBack_FromFrame

func FormatException

func FormatException(tb *Traceback, typeName, message string) string

FormatException prepends typeName: message to a Format(tb) output, matching `traceback.format_exception` for a single (no-chain) exception. The errors package walks the cause/context chain itself and calls FormatException per node.

CPython: Python/traceback.c:L1129 _PyTraceBack_Print

Types

type Entry

type Entry struct {
	File string
	Line int
	Name string
}

Entry is one line of a traceback. Mirrors the data carried by PyTracebackObject (filename, line number, function name).

CPython: Objects/frameobject.h (analog) and Python/traceback.c

type Traceback

type Traceback struct {
	objects.Header
	Entry   Entry
	Next    *Traceback
	TbFrame objects.Object
	TbLasti int
}

Traceback is the linked list of entries that backs Python's `__traceback__`. The next pointer chains older frames; CPython stores the chain in reverse, with the newest frame at the head.

In CPython this is the PyTracebackObject struct exposed as the builtin `traceback` type. The Entry field carries the position data the original v0.3 port used (file/line/name); TbFrame and TbLasti are the slots that match CPython's tb_frame / tb_lasti once a real frame is available. Either the Entry path or the TbFrame path is enough to drive Format.

CPython: Include/cpython/traceback.h:L9 PyTracebackObject

func New

func New(entry Entry) *Traceback

New builds a single-entry traceback. The errors package uses this when v0.3 runtime code wants to attach a position from Go.

CPython: Python/traceback.c:L154 PyTraceBack_Here

func Push

func Push(tb *Traceback, entry Entry) *Traceback

Push prepends a new entry. The result becomes the new head.

CPython: Python/traceback.c:L154 PyTraceBack_Here