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[CLJS-27] Conditional compilation (or reading) Created: 22/Jul/11  Updated: 09/Apr/15  Resolved: 09/Apr/15

Status: Closed
Project: ClojureScript
Component/s: None
Affects Version/s: 0.0-3126
Fix Version/s: 0.0-3196

Type: Enhancement Priority: Major
Reporter: Rich Hickey Assignee: David Nolen
Resolution: Completed Votes: 12
Labels: None

Attachments: File cljs-27.diff     File cljs-27-v2.diff     File cljs-27-v3.diff     File cljs-27-v4.diff     File cljs-27-v5.diff     File cljs-27-v6.diff     File conditional-compilation-clojure.diff     File conditional-compilation-clojurescript.diff    
Patch: Code and Test
Approval: Vetted


As people start trying to write libs that are portable between Clojure and ClojureScript they might need to have a bit of branching on target. N.B. supporting this means a change to Clojure, although it has general utility there as well.

Consider CL #+ #- reader macros - http://www.lispworks.com/documentation/lw50/CLHS/Body/02_dhq.htm

Patch: cljs-27-v6.diff

Related: CLJ-1424, TRDR-14

Comment by Roman Scherer [ 19/Jul/12 8:52 AM ]

The following patches include an implementation of Common Lisp's #+
and #- reader macros to allow conditional compilation/reading for
Clojure and ClojureScript.

The patches add a dynamic variable called features to the
clojure.core and cljs.core namespaces, that should contain the
supported features of the platform in question as keywords.

Unlike in Common Lisp, the variable is a Clojure set and not a list.
In Clojure the set contains at the moment the :clojure keyword, and in
ClojureScript the :clojurescript keyword.

I would like to get feedback on the names that are added to this
variable. Are those ok? Is :jvm for Clojure and :js for ClojureScript
better? Should ClojureScript add something like :rhino, :v8 or
:browser as well?

To run the ClojureScript tests, drop a JAR named "clojure.jar" that
has the Clojure patch applied into ClojureScript's lib directory.

Comment by David Nolen [ 19/Jul/12 12:18 PM ]

This is an enhancement so it probably requires a design page and extended discussion before it will go anywhere. Until that happens I'm marking this is as low priority.

Comment by Roman Scherer [ 19/Jul/12 1:45 PM ]

Ok. If someone could give me write access to the Clojure Dev Wiki I would be happy to start such a design page.

Comment by David Nolen [ 19/Jul/12 5:50 PM ]

If you've sent in your CA request permissions on the clojure-dev mailing list.

Comment by Roman Scherer [ 21/Jul/12 5:45 AM ]

I started a design page for this ticket in the Clojure Dev wiki:

Comment by Stuart Halloway [ 27/Jul/12 1:48 PM ]

Posting my comments over on the design page...

Comment by Alex Miller [ 06/Aug/14 7:42 AM ]

Latest patch updates into current ClojureScript and use of tools.reader/tools.analyzer etc. The reader changes are all in the accompanying tools.reader patch in TRDR-14. This patch adds support to allow a new option "features" which is expected to be a set of keywords. build will inject :cljs into this set. The feature set is maintained in clojure.tools.reader/*features*. set! is enhanced to special-case an update to *features* in the code (presumably a rarely-used feature).

Because tools.reader needs the supporting patch, I left in several changes that pull in a new version of tools.reader - I don't actually expect those to be the correct versions but they are there as a reminder to update all of the proper places.

Comment by Alex Miller [ 11/Sep/14 9:04 AM ]

cljs-27-v2.diff adds ability to load .clj files as well as .cljs files when compiling.

Comment by Alex Miller [ 07/Nov/14 10:55 AM ]

Fresh patch, switch to take .cljc files.

Comment by Alex Miller [ 06/Jan/15 3:04 PM ]

Freshened patch for current CLJS.

Comment by David Nolen [ 06/Jan/15 9:55 PM ]

Alex the freshened patch includes modifications to the compiler version dynamic var and compiler version fn. Can we remove these? Thanks!

Comment by Alex Miller [ 07/Jan/15 12:28 PM ]

Yep, updated to -v5 patch.

Comment by Alex Miller [ 21/Jan/15 4:36 PM ]

Updated to use new tools.reader patch and to remove the ability to dynamically set the features set. The active set of features can be set on startup and are held in the features var in the analyzer.

Comment by David Nolen [ 09/Apr/15 10:32 AM ]

the big issues resolved as of https://github.com/clojure/clojurescript/commit/7ccdffaf8f36a28dec6651248707ac83e6362d79

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