module Logbuch::Messages

Overview

The converters that build the messages of a traced method's lines: the entry line's, the exit line's and the error line's.

Each one is a macro that takes call, a named tuple literal of what is known about the traced method when the program compiles, and expands to the message, which must be a String:

| Key | Example | Notes | | -------------- | ------------------------------ | ------------------------------------- | | type | "Shop::Checkout" | without generic arguments | | method | "place" | | | class_method | false | | | label | "Shop::Checkout#place" | the method value of the line's data | | description | "placing the order" or nil | the annotation's string, as written | | level | "trace" | the method's level | | params | ["order", "coupon"] | the parameters' internal names |

params lists a splat and a double splat under their bare names, and parameters marked @[LogAs(:omit)] or @[LogAs(:redacted)] too; it leaves out an unnamed * and the block parameter.

A program replaces a converter by reopening this module after requiring logbuch. The wrappers are generated once the whole program is read, so the last definition wins, wherever it is:

module Logbuch::Messages
  macro entry_message(call)
    {{ "→ #{call[:label].id}" }}
  end
end

Each message is kept in a constant of the traced type, which the traced call reads. A converter therefore cannot refer to the call's arguments, an expansion that is a string literal costs nothing per call, and a computed one is computed once, the first time it is read.

Defined in:

logbuch/messages.cr

Macro Summary

• entry_message(call)

  The entry line's message: the description, such as placing the order, or > and the label, such as >Shop::Checkout#place.

• error_message(call)

  The error line's message: error and the description, such as error placing the order, or ! and the label, such as !Shop::Checkout#place.

• exit_message(call)

  The exit line's message: done and the description, such as done placing the order, or < and the label, such as <Shop::Checkout#place.

Macro Detail