Nested mixins cannot be accessed inside objects iteration

[maxim-grishaev]

mixin ul(li, t)
    ul
        each val, name in t
            +li(name, val)

mixin li(name, val)
    li= name

+ul(li, {a:1})

Fails with Object #<Object> has no method 'li'.

Whereas the same code but with Array works pretty good:

mixin ul(li, t)
    ul
        each val, name in t
            +li(name, val)

mixin li(name, val)
    li= name

+ul(li, [1,2])

gives

<ul>
<li>1</li>
<li>2</li>
</ul>

[ForbesLindesay]

Using the latest version of jade, your first example outputs:

<ul>
  <li>a</li>
</ul>

If you still believe there is an error, please provide a failing test case (preferably as a pull request).

[maxim-grishaev]

Not sure what the difference between these examples, but this one fails:

- var dbg = {a:1, b:2, c:3}

mixin eachDbg(mxn)
    ul
        each val, name in dbg
            +mxn(name, val)

foo
    mixin tab(name, val)
        tab: a(href="##{name}")= name
    +eachDbg(tab)
    //
    mixin pane(name, val)
        h2= name
        pane(id=id)= val
    +eachDbg(pane)

More info

➜  sync-viewer git:(master) ✗ npm i jade -g
/usr/local/bin/jade -> /usr/local/lib/node_modules/jade/bin/jade.js
[email protected] /usr/local/lib/node_modules/jade
├── [email protected]
├── [email protected]
├── [email protected] ([email protected])
├── [email protected] ([email protected], [email protected], [email protected])
├── [email protected] ([email protected])
├── [email protected] ([email protected])
└── [email protected] ([email protected])
➜  sync-viewer git:(master) ✗ jade --version
1.1.5
➜  sync-viewer git:(master) ✗ which jade
/usr/local/share/npm/bin//jade
➜  sync-viewer git:(master) ✗ cat tmp/mixins.jade | jade

/usr/local/share/npm/lib/node_modules/jade/lib/runtime.js:202
  throw err;
        ^
TypeError: Jade:6
    4|     ul
    5|         each val, name in dbg
  > 6|             +mxn(name, val)
    7|
    8| foo
    9|     mixin tab(name, val)

Object #<Object> has no method 'mxn'
    at Object.eval (eval at <anonymous> (/usr/local/share/npm/lib/node_modules/jade/lib/jade.js:160:8), <anonymous>:41:19)
    at Object.jade_mixins.eachDbg (eval at <anonymous> (/usr/local/share/npm/lib/node_modules/jade/lib/jade.js:160:8), <anonymous>:47:4)
    at eval (eval at <anonymous> (/usr/local/share/npm/lib/node_modules/jade/lib/jade.js:160:8), <anonymous>:79:23)
    at res (/usr/local/share/npm/lib/node_modules/jade/lib/jade.js:161:38)
    at Socket.<anonymous> (/usr/local/share/npm/lib/node_modules/jade/bin/jade.js:127:20)
    at Socket.emit (events.js:117:20)
    at _stream_readable.js:929:16
    at process._tickCallback (node.js:419:13)

[ForbesLindesay]

Yes, because mixins are not variables like that. Instead they are their own special kind of construct. You could implement something like what you're after as:

• var dbg = {a:1, b:2, c:3}

mixin eachDbg(mxn)
ul
each val, name in dbg
- mxn(name, val)

foo
    mixin tab(name, val)
        tab: a(href="##{name}")= name
    +eachDbg(jade_mixins['tab'])
    //
    mixin pane(name, val)
        h2= name
        pane(id=id)= val
    +eachDbg(jade_mixins['pane'])

// we are messing with jade internals (i.e. accessing jade_mixins directly)
// so we have to stop it from optimizing things
if false
  +#{''}

Note that if you do that, it could break with any version of jade, since jade_mixins is intended to be internal.

Alternatively, a simpler way is to use the fact that you can dynamically invoke mixins:

- var dbg = {a:1, b:2, c:3}

mixin eachDbg(mxn)
    ul
        each val, name in dbg
            +#{mxn}(name, val)

foo
    mixin tab(name, val)
        tab: a(href="##{name}")= name
    +eachDbg('tab')
    //
    mixin pane(name, val)
        h2= name
        pane(id=id)= val
    +eachDbg('pane')

Here, we pass the name of the mixin we want to invoke, and then we invoke it by name using +#{mxn}

[maxim-grishaev]

Thank you @ForbesLindesay!

I actually already found yor second solution on SO =)
But as I see this, construction looks like a bunch of dark magic, so I made a "clumsy" feature request #1608
Actually, if blocks would be able to accept parameters like mixins, the whole problem would be solved...
Is there any solution for this in 2.0?

[maxim-grishaev]

BTW, this solution isn't too fail-proof and any mistake in mixin name will lead to REALLY WEIRD errors

[ForbesLindesay]

Yes, we could definitely do better with reporting errors for undefined mixins.

I quite like the suggestion in #1608 so may consider that feature in the future.We might also be able to use a similar idea to support multiple blocks in a single mixin (another feature request that comes up from time to time).

[maxim-grishaev]

I quite like the suggestion in #1608 so may consider that feature in the future

Cool, thanks!

[Artazor]

Seems that I've implemented syntax/semantics very close to what is needed. You can check

pugjs/with#3 - here is description of what's done
https://github.com/Artazor/jade - my fork of jade (extended conservatively)

Waiting for @ForbesLindesay to take a look on the changes