mirror of https://github.com/golang/go.git
5a9463bda7
The existing type checker was relying on augmenting ast.Object fields (empty interfaces) for its purposes. While this worked for some time now, it has become increasingly brittle. Also, the need for package information for Fields and Methods would have required a new field in each ast.Object. Rather than making them bigger and the code even more subtle, in this CL we are moving away from ast.Objects. The types packge now defines its own objects for different language entities (Const, Var, TypeName, Func), and they implement the types.Object interface. Imported packages create a Package object which holds the exported entities in a types.Scope of types.Objects. For type-checking, the current package is still using ast.Objects to make this transition manageable. In a next step, the type- checker will also use types.Objects instead, which opens the door door to resolving ASTs entirely by the type checker. As a result, the AST and type checker become less entangled, and ASTs can be manipulated "by hand" or programmatically w/o having to worry about scope and object invariants that are very hard to maintain. (As a consequence, a future parser can do less work, and a future AST will not need to define objects and scopes anymore. Also, object resolution which is now split across the parser, the ast, (ast.NewPackage), and even the type checker (for composite literal keys) can be done in a single place which will be simpler and more efficient.) Change details: - Check now takes a []*ast.File instead of a map[string]*ast.File. It's easier to handle (I deleted code at all use sites) and does not suffer from undefined order (which is a pain for testing). - ast.Object.Data is now a *types.Package rather then an *ast.Scope if the object is a package (obj.Kind == ast.Pkg). Eventually this will go away altogether. - Instead of an ast.Importer, Check now uses a types.Importer (which returns a *types.Package). - types.NamedType has two object fields (Obj Object and obj *ast.Object); eventually there will be only Obj. The *ast.Object is needed during this transition since a NamedType may refer to either an imported (using types.Object) or locally defined (using *ast.Object) type. - ast.NewPackage is not used anymore - there's a local copy for package-level resolution of imports. - struct fields now take the package origin into account. - The GcImporter is now returning a *types.Package. It cannot be used with ast.NewPackage anymore. If that functionality is still used, a copy of the old GcImporter should be made locally (note that GcImporter was part of exp/types and it's API was not frozen). - dot-imports are not handled for the time being (this will come back). R=adonovan CC=golang-dev https://golang.org/cl/7058060 |
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README
This is the source code repository for the Go programming language.
For documentation about how to install and use Go,
visit http://golang.org/ or load doc/install.html in your web browser.
After installing Go, you can view a nicely formatted
doc/install.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install.html.
Unless otherwise noted, the Go source files are distributed
under the BSD-style license found in the LICENSE file.
--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set
the environment variable $GOROOT to the full path of the go
directory (the one containing this README). You can omit the
variable if you unpack it into /usr/local/go, or if you rebuild
from sources by running all.bash (see doc/install.html).
You should also add the Go binary directory $GOROOT/bin
to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might
put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See doc/install.html for more details.