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If you have a struct containing ‘field’, eg:
type t = { field : int }
then previously to pattern-match on this type, eg. in function
parameters, you had to write:
let f { field = field } =
(* ... use field ... *)
In OCaml >= 3.12 it is possible to abbreviate cases where the field
being matched and the variable being bound have the same name, so now
you can just write:
let f { field } =
(* ... use field ... *)
(Similarly for a field prefixed by a Module name you can use
‘{ Module.field }’ instead of ‘{ Module.field = field }’).
This style is widely used inside the OCaml compiler sources, and is
briefer than the long form, so it makes sense to use it. Furthermore
there was one place in virt-dib where we are already using this new
style, so the old code did not compile on OCaml < 3.12.
See also:
https://forge.ocamlcore.org/docman/view.php/77/112/leroy-cug2010.pdf
This program generates a large amount of code and documentation for all the daemon actions. To add a new action there are only two files you need to change, 'actions_*.ml' to describe the interface, and daemon/<somefile>.c to write the implementation. After editing these files, build it (make -C generator) to regenerate all the output files. 'make' will rerun this automatically when necessary. IMPORTANT: This program should NOT print any warnings at compile time or run time. If it prints warnings, you should treat them as errors. OCaml tips: (1) In emacs, install tuareg-mode to display and format OCaml code correctly. 'vim' comes with a good OCaml editing mode by default. (2) Read the resources at http://ocaml.org/learn/ (3) A module called 'Foo' is defined in one or two files called 'foo.mli' and 'foo.ml' (NB: lowercase first letter). The *.mli file, if present, defines the public interface for the module. The *.ml file is the implementation. If the *.mli file is missing then everything is exported. Some notable files in this directory: actions_*.ml The libguestfs API. proc_nr.ml Procedure numbers associated with each API. structs.ml Structures returned by the API. c.ml Generate C API. <lang>.ml Generate bindings for <lang>. main.ml The main generator program. Note about long descriptions: When referring to another action, use the format C<guestfs_other> (ie. the full name of the C function). This will be replaced as appropriate in other language bindings. Apart from that, long descriptions are just perldoc paragraphs. Note about extending functions: In general you cannot change the name, number of required arguments or type of required arguments of a function, since this would break backwards compatibility. You may add another optional argument, *if* the function has >= 1 optional arguments already. Add it at the end of the list. You may add optional arguments to a function that doesn't have any. However you *must* set the once_had_no_optargs flag to true, so that the relevant backwards compatibility bindings can be added.