[tahoe-lafs-trac-stream] [Tahoe-LAFS] #2377: replace 'cond and one or tother' idiom with 'one if cond or tother'

[Tahoe-LAFS]

#2377: replace 'cond and one or tother' idiom with 'one if cond or tother'
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     Reporter:  daira   |      Owner:  daira
         Type:  defect  |     Status:  new
     Priority:  normal  |  Milestone:  undecided
    Component:  code    |    Version:  1.10.0
   Resolution:          |   Keywords:  cleanup
Launchpad Bug:          |
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Description changed by daira:

Old description:

> In Python 2.5, the nearest equivalent to C's `cond ? one : tother` was
> the idiom `cond and one or tother`.
> In Python 2.6, a more precise equivalent is `one if cond else tother`.
>
> The former is error-prone: it evaluates to `tother` when `one` is falsy,
> which is the wrong thing. Since we now depend on Python 2.6, we can
> always use the latter.
>
> ("t'other" is Northern English dialect for "the other", if you were
> wondering about that.)

New description:

 In Python pre-2.5, the nearest equivalent to C's `cond ? one : tother` was
 the idiom `cond and one or tother`.
 In Python 2.5+, a more precise equivalent is `one if cond else tother`.

 The former is error-prone: it evaluates to `tother` when `one` is falsy,
 which is the wrong thing. Since Tahoe-LAFS requires at least Python 2.6,
 we can always use the latter.

 ("t'other" is Northern English dialect for "the other", if you were
 wondering about that.)

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2377#comment:1>
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