Module Injector_events.Make

This module provides wrappers to declare events without having to declare a module and apply the Make functor. They are pretty-printed as <DOC> (<PARAMETER> = <VALUE>, ...) (unless there is no parameter at all, in which case they are printed as <DOC>). You may also use braces to inline some parameters in <DOC>. In the example below, hash is inlined.

For consistency, it is suggested that log messages do not start with a capital letter and do not end with a period. For instance, write ~msg: "started something important" instead of ~msg: "Started something important.". The reason is that messages that do not inline all of their parameters are followed by the remaining parameters in parentheses, and a period does not (arguably) look great in those cases. If it does not end with a period, it is not a sentence and thus capitalizing the first word does not make much sense either.

Declare events with one of the declare functions, for instance: let inject = Internal_event.Simple.declare_2 ~name: "inject" ~msg: "injected block {hash}" ("level", int) ("hash", string) You must declare events only once for a given name. Usually you should thus declare them as global variables.

There is one declare_n function for each number n of parameters. For instance, the above example uses declare_2 because it has two parameters: level and hash.

Each parameter has a default pretty-printer that you can override using the ?ppX parameters. For instance, to override the default pretty-printer of the second parameter, pass a ~pp2 argument. This allows to, for instance, print only the first element of a list, remove quotes for strings, decide how many decimal digits are printed for floats, etc.

The default pretty-printer behaves as follows:

• for base types (booleans, integers, strings, floats), it uses OCaml syntax;
• for strings which are longer than 64 characters, it prints only the first characters followed by an ellipsis [...];
• for null or similar encodings, it prints N/A;
• for unions of Null and another encoding e (this is the encoding of options), it prints null for Null and uses e to decide how to print the value otherwise;
• for other constructed values (arrays, lists, objects, tuples, unions, and recursive types), it prints a placeholder like <list> or <obj> (see remark below).

Because constructed values such as lists and objects are printed as placeholders such as <list> and <obj> and thus do not give any information, those parameters are not automatically added in parentheses at the end of the messages. You can override the default pretty-printer of those parameters to override this behavior. In that case, values will be printed if your pretty-printer does not output an empty string. Note that you should also override the default pretty-printer of constructed types that you inline using braces, as they would be printed using the placeholder otherwise.

Then emit this event with some parameters like this: Internal_event.Simple.emit inject (42, "BL654654654645654654564") This event will be printed as: injected block BL654654654645654654564 (level = 42)

For all declare functions, the default value for level is Info.