<c-void>, warning removal, external linkage for variables

[iglennrogers]

Sorry, this is as one blob - slight issue of messing up the repository.

1. typedef void FILE now produces a <c-void> rather than <void> which produces an error.
2. Making various slots constant (removing -setter not used warnings) and commenting out some unused slots, bringing the number of warnings in melange & melange-parser to 1.
3. Melange now produces code for variables, with an additional external: #t in the variable or include-file clause of the interface definition for external linkage.

[hannesm]

first of all: big thanks.

it would be even better if you could separate 1, 2 and 3 in separate commits (using git add --interactive).

I actually do not completely understand 3 - the changes are that external is passed around in find-dylan-name and compute-dylan-name - but the only user is write-declaration (which indirectly accesses this argument in define method find-dylan-name (decl :: <variable-declaration>, mapper :: <function>, prefix :: <string>, containers :: <sequence>, rd-only :: <boolean>, sealing :: <string>, external :: <boolean>, #next next-method) => (result :: <string>);

Or do I miss something?

[hannesm]

(somehow I've the feeling that the complexity external adds is quite high (by adding an argument to every method), but I don't have a good idea for an alternative solution)

[iglennrogers]

Splitting in progress, or rather a series of blow-by-blow sessions with diff :( Should get it finished this evening.

You're right that there's a lot of extra work involved with external, having to pass it as a parameter everywhere in sight, just to use it twice. Just about the only way around it is to assemble the mapper ... external parameters into a class and pass that instead, reassembling it as required. Worth thinking about if another parameter needs to be added on for some reason.

The working/real code does the following (from memory):

• Change the <variable-declaration> to derive from <container-options> so it can include read-only etc members.
• Change the parser so that it accepts external: phrases in the interface definition.
• Add a new method to write out a define c-variable clause.
• Add a line merging the external: setting into the global container options.

[waywardmonkeys]

I've hand-merged parts of this in my next branch that is landing ... but not the "Add definition of c-variable ..." part yet.

I don't like adding the external stuff everywhere (and what's that for?).

[waywardmonkeys]

For reference, my branch is here: https://github.com/waywardmonkeys/melange/commits/misc-improvements

I'm hoping to do more stuff on it and land it within a couple of days.

[iglennrogers]

The external stuff is for global variables, whether they need to imported from another library, or whether they are part of a c-file within the dylan library. See "http://opendylan.org/documentation/library-reference/c-ffi/index.html#c-ffi:c-ffi:definec-variable" for reference. It certainly feels like a lot of effort, for something that shouldn't be used very often.