c.t.n.move: does not support to move .cljc files

Question

it seems that c.t.n.move did not get any reader conditionals love. I use this namespace to power (link: https://github.com/benedekfazekas/mranderson text: mranderson): a source inlining tool used by cider-nrepl and refactor-nrepl in order to avoid clashes with the code/projects their users work on. lately we started adding dependencies to refactor-nrepl (well, tools.namespace itself) which may use .cljc files. source inlining started failing for these source files.

Answer 1

Comment made by: stuart.sierra

Good idea - glad to see how people are actually using tools.namespace in other dev cools.

Could this be extended further to take 'platform' as a parameter, as in {{c.t.n.find}} or {{c.t.n.dir}}?

(I deliberately excluded {{c.t.n.move}} to limit the scope of changes in 0.3.0, but your patch demonstrates that it may not not be such a difficult change to make.)

Answer 2

Comment made by: benedek.fazekas

first patch does what you asked for I hope. Kept original signiture of {{move-ns}} for backward compatibility: {{clj}} platform used by default.

second patch is pushing this a bit further: if platform is not provided it tries to guess it based on the file's extension of the old-sym. you might see this as over complication: feel free to pick the first patch then.

Answer 3

Comment made by: stuart.sierra

Thanks for working on these patches. I did some more testing, and uncovered some more complications.

Guessing the file extension leads to unpredictable results, because you don't know which file gets moved. It's not uncommon to have both {{.clj}} and {{.cljs}} version of the same namespace, for example with {{:require-macros}} in ClojureScript.

Unfortunately, even specifying a "platform" argument doesn't completely solve the problem, because you can have {{.cljc}} file at the same time as {{.clj}} and {{.cljs}}. This may not be common, but it's explicitly allowed for in the (link: http://dev.clojure.org/display/design/Reader Conditionals text: design of reader conditionals). For example, a library may have a platform-neutral .cljc file and override it with a platform-specific file. In this case, even if you specify a "platform" argument, you still can't control which file gets moved.

So now I think the only way for an operation like "move namespace" to make sense is to move all the files defining that namespace, preserving their file extensions. This seems like what one would want from a user perspective as well.

So {{move-ns}} should take new/old symbols, find all the matching files with any extension, move/rename them all while preserving extensions, then apply the textual transformation to all .clj, .cljs, and .cljc files.

If we're searching for files, we might as well eliminate the need to specify the source path, so this also relates to TNS-39.

Answer 4

Comment made by: benedek.fazekas

I have not abandoned this ticket or the patches but it seems it is related to a bigger problem in terms of supporting multiplatform projects therefore related to TNS-38 too.

I am also contemplating the wider context: move-ns is not only used in mranderson for source inlining but there is a refactor-nrepl feature ((link: https://github.com/clojure-emacs/clj-refactor.el/wiki/cljr-rename-file-or-dir text: rename file or dir)) which basically reimplements this functionality using other parts of TNS.

The mranderson story for me is about exploring different ways of dependency handling really, there was a good (link: https://skillsmatter.com/skillscasts/7251-lightning-talks-day-2 text: lightning talk) by Glen Mailer summarising the problem on clojureX this year. My ideas are along creating local, deeply nested dependencies and perhaps enhance the ns macro to be able to load them -- not even sure that is feasible. This would eliminate the need for source inlining and more importantly would be much more hygienic approach I think.

Hope this makes sense. Sorry for the brain dump which is obviously exceeds the scope of this ticket.

Answer 5

Reference: https://clojure.atlassian.net/browse/TNS-37 (reported by benedek.fazekas)