[Omake] Newbie: removing quotes for command

[Aleksey Nogin]

On 21.03.2007 07:00, Hugo Ferreira wrote:

> I have used:
>     INCLUDE = $(addprefix -I , $(INCLUDES))
> and
>     INCLUDE = $(mapprefix -I , $(INCLUDES))
> 
> But when the target executes I get:
> 
> ocamlc "-I " . "-I " ../res_stck "-I " ../qalist "-I " ../term "-I " 
> ../symbl_tbl "-I " ../compile -dtypes -g -c parser.mli
> 
> ...which breaks. How do I get rid of the quotes to obtain:
> 
> ocamlc -I . -I ../res_stck -I ../qalist -I ../term -I ../symbl_tbl -I 
> ../compile -dtypes -g -c parser.mli

The issue here is that in OMake the spaces are, in general, significant. 
Your addprefix call had a space before the "," and that is where the 
"extra" spaces came from. The quotes is just something that the 
pretty-printer added to emphasize that the arguments contain spaces, 
they are not a part of the actual value.

In general, for figuring out things like that, I would recommend using 
OMake's interactive shell osh that makes it easy to see what's going on.

E.g. consider the following in osh

% INCLUDES[] = a b c
- : <array
        "a" : Sequence
        "b" : Sequence
        "c" : Sequence>
        : Array
% addprefix(-I, $(INCLUDES))
- : <array
        <sequence "-I" : Sequence "a" : Sequence> : Sequence
        <sequence "-I" : Sequence "b" : Sequence> : Sequence
        <sequence "-I" : Sequence "c" : Sequence> : Sequence>
        : Array
% addprefix(-I , $(INCLUDES))
- : <array
        <sequence "-I " : Sequence "a" : Sequence> : Sequence
        <sequence "-I " : Sequence "b" : Sequence> : Sequence
        <sequence "-I " : Sequence "c" : Sequence> : Sequence>
        : Array


BTW, is there some reason why you are implementing your own build 
recipes for OCaml (note that at the moment you recipes are missing such 
things as dependency scanning, which may result in all kinds of 
problems) instead of using the existing build/OCaml.om that comes with 
OMake?

> I have even attempted to use my own function:
> 
> F(X, Y) =
>     T =
>     foreach (Z, $(X))
>         T = $(T)$(Y)$(Z)
> 
> #INCLUDE = $( F $(INCLUDES), -I )

Same here - you left a space before the ")"!

> Can anyone also explain how/why/when values are converted to/from a string?

This is a really good question. Unfortunately, this is not as systematic 
  as it probably should be and is not much documented yet.

In general:
  - An explicit quotation ($"..." or $'...') would give you a string.

  - A significant number of built-in functions turn (some of) their 
arguments into a string or a list of strings (breaking over the unquoted 
whitespace and array boundaries). For example,
     - String:
         case, match (the argument being matched)
         getenv, setvar, concat, removeprefix (first argument)
         setenv, get-registry, getvar (all arguments)
	split (separator argument, when given)
     - List of strings:
         string, string-escaped, quote, defined, defined-env, unsetenv 
(the first and only argument)
         equal (both arguments)
         split, concat, removeprefix (last argument)
         addsuffixes (first argument)

Usually, the functions only do that "when they need to do a string-like 
operation on its argument". For example, the split function has to 
manipulate a string representation of its argument, and the same is true 
for the removesuffix. On the other hand, addsuffix is not really a 
string operation (any two values can be concatenated, they do not really 
have to be strings for that), so it does not stringify its argument. 
Some functions, however, do stringify their arguments a bit 
inappropriately - for example, addsuffixes currently does, although it 
probably should not.

At the moment, the only way to figure this out for sure (other than 
manually testing) is to find the code for a built-in function in the 
src/builtin directory of the source tree - 
http://svn.metaprl.org/viewvc/mojave/omake-branches/0.9.8.x/src/builtin/ 
- and look for instances of the string_of_value and strings_of_value 
calls :-(

Aleksey

-- 
Aleksey Nogin, Research Staff Member
Advanced Technologies Department, Information & System Sciences Lab
HRL Laboratories, LLC, Malibu, CA