[Python-Dev] displayhook behavior in pdb

[Paul Moore]

2009/9/16 Michael Foord <fuzzyman at voidspace.org.uk>:
> Georg Brandl wrote:
>>
>> May I have a short vote on this issue:
>>
>>   http://bugs.python.org/issue6903
>>
>> In short, pdb (since 2.6) uses a separate displayhook in order to avoid
>> _ being reassigned (which screws up debugging apps that use _ as gettext).
>> In that displayhook, I did not add the suppression of printing None, as
>> it can be confusing to look at variables and get no output:
>>
>> (Pdb) foo
>> 1
>> (Pdb) bar
>> (Pdb)
>>
>> (You could argue that this is what the "p" command is for though.)
>>
>> Now in Python 3, where print is a function, if you call print in a loop
>> (e.g. to debug a list or dictionary, as it is advertised in the pdb docs
>> under the "alias" command), the output has the printed values interspersed
>> with "None"s.
>>
>> Now, what is the lesser evil?
>>
>>
>
> IMO not showing the extraneous Nones is preferable.

I agree (although I don't use pdb, so my view shouldn't be given too
much weight...)
Paul.