Instrument iterables ala jinja ?

[sqlalchemy-bot]

Migrated issue, originally created by Michael Bayer (@zzzeek)

i.e. user does this:

% for x in collection:
    % if lastelement:
    % endif
% endif

we see the magic name "lastelement". We then compile to this:

% for lastelement, x in __M_marklast(collection):
    % if lastelement:
    % endif
% endif

easy !

tentative 0.3 feature. May come out.

---

Attachments: loop_instrumentation.patch | loop_instrumentation.2.patch | 125.patch

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed title from "Instrument interables ala jinja ?" to "Instrument iterables ala jinja ?"

[sqlalchemy-bot]

Philip Jenvey (@pjenvey) wrote:

I don't like this kind of magic. Some of the loop attributes Jinja provides could use enumerate or itertools.cycle instead, only the ones taking into account the end index of the loop aren't easily done

http://jinja.pocoo.org/2/documentation/templates#for

But how useful are those in practice anyway? Useful enough to warrant the magic? In some simpler cases you can even replace a check for the end of the loop with a check for the beginning of the loop, e.g.

% for foo in bar:
   ${foo.name}
   % if not last:
       ,
   % endif

# ->

% for i, foo in enumerate(bar):
    % if i != 0:
        ,
    % end if
    ${foo.name}

[sqlalchemy-bot]

Anonymous wrote:

It's very useful to have access to first, last and cycle item. Productivity boost:)

This is the second feature lacking in Mako (just after not having escape char for %) for my uses cases.

[sqlalchemy-bot]

Anonymous wrote:

Also keep in mind for nested loops.

Something like this would come in handy:

% for i in foobar as first_loop:
  % for j in foobar:
      % if first_loop.first:
          first!
      % endif
   ...

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

pushing this off since I'd like to fast track 0.3 a bit

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• removed labels: bug, caching
• added labels: compiler, feature
• changed milestone from "0.3" to "0.4"

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

this is a nice to have but i think 0.4 needs to come out faster than this

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• removed milestone (was: "0.4")

[sqlalchemy-bot]

Anonymous wrote:

It's safe to ignore the first loop_instrumentation patch. The second one has all the same changes plus a from __future__ import with_statement for people still using python2.5.

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

let's move over to https://bitbucket.org/zzzeek/mako-loop for dev on this

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

merged it in 6e7ad2d - spectacular !!

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed status to closed