#hoplon

Hi, I've been looking at boot lately, and i have troubles finding an answer to one question:

How does boot determine whether task needs to be run or cached output can be used instead? Does it do this at all or task itself needs to handle this?

Tasks need to handle this themselves

Usually it is super simple, check for example boot-less: https://github.com/Deraen/boot-less/blob/master...

Several tasks use the same logic to get list of changed input files and only run compilation etc. for those files

Oh, thanks. Im using your lib by the way, Deraen! Just never looked at its code:)

boot-bower doesnt use input files though, it generates them from the invocation parameters. So in fact I'd need to detect change in parameters...

That's why I asked if boot does things like that, seems like it could (it manages some cache after all)

Hmm, the last-less is an atom that's part of captured state of the task. So am I right it does not work between invocation and only in some sort of watch mode?

True

Other than maven cache, there is (usually) no cache between Boot invocations

E.g. Cljs build is always done from clean, similar to running lein clean before build

Always = After Boot invocation

We did talk about having cache-dirs in addition to current tmp-dirs

I don't remember if this got ever implemented

Interesting - seems like it favours 'watch' type of tasks but still, the initial overhead is quite big

https://github.com/boot-clj/boot/blob/fb64f8e72... https://github.com/boot-clj/boot/blob/fb64f8e72...

Yeah I guess with bower task it would make sense to keep the component dir between the runs

similar to how maven cache works

hmm though bower also has "global" cache, so it shouldn't download everything again each time? ~/.cache/bower

Well, to be honest it would make to cache everything, if side effects are under control, that is, tasks can be considered referentially transparent, then maybe it would be quite safe?

Yeah I think that was the idea we had with cache dirs

We had idea to use them to make initial Cljs compilation faster, but that got never implemented as Cljs initial compilation got faster

In my scenario bower deps are not changing often, very rarely even, it is a waste of time currently. Will check bower cache anyway, firstly

A easy way for bower to cache stuff would be just to use local directory instead of temp dir

The task could use e.g. ./bower_components dir in the work dir, write stuff to that, and add it to fileset using add-resource so the files are available in the classpaht

and to other tasks

Work dir- you mean dir where sources are?

Anyway, thanks for pointers, will be playing with it later on

work dir = the dir with build.boot

and there the source-dirs etc. are

Deraen, I've found also this: https://github.com/boot-clj/boot/blob/fb64f8e72.... This seems to be doing the trick for me