Pdb;pdb.set_trace() alternative

Plone Support Add-on Development
1

Quick question.
Currently when I'm debugging in Plone I tend to use:

 import pdb;pdb.set_trace()

Is anyone using something different/better?

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2

I'm using Products.PDBDebugMode, I can't develop without it. You enter a pdb automatically when there is an exception.

3

Hello,
I also use that, but I prefere using

import ipdb; ipdb.set_trace()

And I also use 2 packages, It depends on what I have to debug :

  1. iw.debug : With this package, I can append /ipdb after any url. Then you arrive in ipdb shell and context is url (example : /plone/path/to/my/object/to/debug/ipdb, debug object is context in your terminal)
  2. Products.PDBDebugMode : With this package you arrive in pdb shell when an exeption is raised by Zope/Plone.
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4

With Products.PDBDebugMode, you have a view /@@pdb that you can call on any context too.

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5

@bsuttor and @vincentfretin very useful. I've come across PDBDebugMode before but these additional tips should make my life even easier.

6

You can also easily debug templates, when you using Chameleon (five.pt) as TAL engine:

Just include:

< tal:something >

<?python import ipdb; ipdb.set_trace() ?>

< /tal:something >

In console you just write ipdb> pp econtext to get the current local variables. (Note: In some template bindings it's rcontext.) Other than that, I can suggest to exploit the new commands of ipdb such as pinfo to display information about an object (docstring, signature, path to source, etc.).

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7

A refinement for this trick!

<?python locals().update(econtext); import ipdb; ipdb.set_trace() ?>

or, for Python >= 3.7:

<?python locals().update(econtext); breakpoint() ?>

Which loads in the locals the variables defined in the template (econtext)!

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8

Note that the Chameleon trick only works in Zope 3 templates, so not in skin templates and not in TTW templates.

If you find that you can use it in those, then you should install the April 2016 hotfix. :slight_smile: See https://plone.org/security/hotfix/20160419/bypass-restricted-python

3 Likes
9

I'm glad I asked @pgg, @alert and @mauritsvanrees. Lots of useful information here :).

10

Besides the solutions already discussed, I also heavily use interactive debugging via "bin/{client1|instance} debug". It gives you an interactive Python interpreter with access to Zope's root object (bound to "app"). In the interpreter, you can do "normal" Python debugging.

11

I do use bin/instance debug, mostly when I'm developing custom scripts.

12

I've been using pdb++ for a while now and really like it. The best feature is the command ll which is like l but always shows the current menthod in full. I'll also give a talk on debugging at the upcoming conference where I'll show some more nice tricks :smiley:
@alert: nice trick updating the locals. I'll add that to https://www.starzel.de/blog/magic-templates-in-plone-5

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13

Great! That post is awesome :slight_smile:

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14

Every newbie should bookmark this thread under the heading "Plone debugging" :slight_smile:

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15

Or you could update the manual?

16

@djay ... Very true sir.

17

And let's not forget the excellent Plone Reloader Chrome extension, for when you want to quickly make some changes to a python file (such as adding/removing pdb) and avoid restarting Zope. Beats going to http://localhost:8080/@@reload, plus has some Diazo debugging goodies:

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18

Indeed @djay. It would be a nice addition to https://docs.plone.org/develop/debugging/pdb.html

19

I look forward to seeing the documentation pull request! :wink:

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20

The contributor's problem again, rs. We already have your e-mail but we still need to address some stuff with the legal department before being able to do PRs to /plone, at least we're already doing it to /collective.