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Signed-off-by: Mike McClurg <>
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1 parent 71a52d7 commit e99a8383846fdf0048e0c88e7d539e3b701de5a8 Mike McClurg committed Oct 18, 2012
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@@ -126,3 +126,50 @@ just throwing an exception on error, we can do error reporting. Though
we could just do failwith "foo", or create a custom exception with the
loggin data we need, so this might not be such a killer feature.
+* [2012-10-17 Wed] Success!
+So I've worked out the filter to the point where we can generate an
+implementation file from an interface file. The whole thing isn't done
+yet, but the structure of both the filter code and the output of the
+filter is basically finished.
+We have a filter which iterates over a signature file, and builds up
+state in an object. The object has methods for generating the AST of
+the mocked module and the Expect module, which we use to set up the
+mock module for tests. Almost all of my initial skeleton
+has been implemented.
+Here are some thoughts about this work:
+ - Using templates. I thought about using template ml files to hold
+ code which could be included in the generated modules. Because
+ these files couldn't easily be compiled separately, since they
+ were missing dependencies of their own, this didn't work out. I
+ also ran into problems with including a template module too early,
+ and the Hashtbl type not being fully specified at that point. It
+ just didn't provide the benefit I was looking for.
+ - Inserting the mocked module's name. I'm still not sure how we'll
+ do this, since the sig filter won't know at filter time the name
+ of the module type it's operating on. My current idea is to use
+ the 'camlp4 -str <implem>' option to pass in some fragment,
+ say, 'let module_name = FooModule', on the command line, which
+ will let us run a str_filter along with the sig_filter. We could
+ pass in various options this way, I suppose. (Update: doesn't look
+ like this will work, because we can only operate on one sig/str
+ object at a time. You can't pass in a filename and a -str "".)
+ - Objects. Turns out that objects are surprisingly lightweight to
+ use. They seem to be the perfect thing to use here, since we need
+ to build up state while we're filtering, and then perform actions
+ on that state while generating the new module.
+ - Using revised syntax. There are a few good references about
+ revised syntax, but even they tell you to just print some sample
+ original syntax out as revised syntax for some tricker bits. The
+ command line tool to do this is 'camlp4orf -printer r'.
+ - Using revised syntax for function quotations. You really can't do
+ <:str_item< value f a = a >>. Just do <:str_item< value f = fun [
+ a -> a ] >>.

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