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[TNS-36] Use java.classpath Created: 26/Jul/15  Updated: 31/Jul/15

Status: In Progress
Project: tools.namespace
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Stuart Sierra Assignee: Stuart Sierra
Resolution: Unresolved Votes: 0
Labels: None

Attachments: Text File 0001-TNS-36-Use-java.classpath.patch     Text File 0001-TNS-36-Use-java.classpath.patch    
Patch: Code


Past versions of tools.namespace copied some functions (e.g. one, two) from java.classpath to avoid a dependency.

However, since the addition of CLASSPATH-5, tools.namespace has been missing some functionality necessary to fully resolve the classpath in some environments.

The purpose of this ticket is to 1) add a dependency on java.classpath; and 2) replace the duplicated functions in tools.namespace with their equivalents in java.classpath.

No public APIs in tools.namespace will be affected.

[TNS-35] Read/analyze ClojureScript and conditional read sources Created: 24/Jul/15  Updated: 31/Jul/15

Status: Open
Project: tools.namespace
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Stuart Sierra Assignee: Stuart Sierra
Resolution: Unresolved Votes: 1
Labels: None


Clojure 1.7 and ClojureScript 3308 introduced support for the Conditional Reader.

tools.namespace started out as a Clojure-only library. Support for the conditional reader was added in TNS-34, but it was hard-coded for Clojure (.clj and .cljc) files only.

Some high-level features of tools.namespace, such as code reloading via c.t.n.repl/refresh, are coupled to the Clojure(JVM) implementation, and could not easily be ported to ClojureScript. I regard that as a non-issue for now, since other tools (e.g. Figwheel) exist to do reloading in ClojureScript.

However, other features of tools.namespace, such as namespace dependency analysis, do not depend specifically on Clojure(JVM). It might be useful to apply those tools on ClojureScript source files.

The deeper problem is the multi-layered structure of tools.namespace. The Clojure/ClojureScript distinction only really matters in the "lower" layers such as c.t.n.file and c.t.n.parse, but the layered structure makes it awkward to pass options through from the "higher" layers such as c.t.n.dir and c.t.n.find.

See also comments on TNS-29.

This ticket is a place to capture work and notes about this problem.

Comment by Stuart Sierra [ 24/Jul/15 3:23 PM ]

Breakdown by namespace:

c.t.namespace is deprecated

c.t.n.dependency has no JVM-specific coupling, can be trivially ported to .cljc

c.t.n.track has no JVM-specific coupling, can be trivially ported to .cljc

c.t.n.parse has read-ns-decl calling clojure.core/read, which always uses default platform feature :clj. Can be modified to support reading .cljc files with the :cljs feature by replacing clojure.core/read with tools.reader.

c.t.n.file defines clojure-file? hard-coded to .clj and .cljc since TNS-34. Would be trivial to add clojurescript-file?.

c.t.n.dir calls c.t.n.file/clojure-file?

c.t.n.repl calls c.t.n.dir/scan

c.t.n.find calls c.t.n.file/clojure-file? and also uses hard-coded .clj and .cljc as file extensions to search within JAR files.

c.t.n.move is hard-coded to .clj files but is still "alpha" and not widely used

Comment by Laurent Petit [ 24/Jul/15 6:01 PM ]

couldn't `read-ns-decl` call `clojure.core/read` with `:read-cond` and `:features` options set appropriately? Is it really necessary to add `tools.reader` as a dependency (I would avoid it if possible)?

Comment by Stuart Sierra [ 25/Jul/15 10:10 AM ]

The reason you can't just pass different options to clojure.core/read is because, on Clojure(JVM) read will always add the platform feature :clj. There is no way to call read and force it to omit the platform feature.

See the Reader Conditionals design page, "The platform feature (:clj) will always be present."

Comment by Laurent Petit [ 25/Jul/15 3:10 PM ]

Oh, I didn't know that. It's kind of a shame, no, since it is well known that ClojureScript is compiled via Clojure (JVM) ...

Comment by Stuart Sierra [ 25/Jul/15 6:51 PM ]

As far as I know, ClojureScript has used tools.reader instead of clojure.core/read for some time.

Comment by Stuart Sierra [ 26/Jul/15 10:00 AM ]

My current thinking is:

c.t.n.dependency and c.t.n.track are platform agnostic.

c.t.n.file and c.t.n.parse can be extended to support Clojure & ClojureScript by adding an optional argument read-opts passed through to tools.reader/read.

c.t.n.find can be extended with optional arguments to select a "platform," either Clojure or ClojureScript, which will encapsulate both valid file extensions and reader options.

Reload/refresh functionality will remain Clojure(JVM) only for now: c.t.n.dir, c.t.n.reload, and c.t.n.repl.

c.t.n.move is still alpha and does not even support .cljc files. It can be handled under separate tickets or deprecated.

Work-in-progress visible on branch TNS-35-cljs-experiments currently at commit e9327295

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