On 04/03/2017 10:27 AM, Deborah Swanson wrote:
Dennis Lee Bieber wrote, on April 03, 2017 9:35 AM
On Mon, 3 Apr 2017 07:30:40 -0700, "Deborah Swanson"
<pyt...@deborahswanson.net> declaimed the following:
Clearly there's more to be found in nooks, crannies and
byways in the
docs than you'll get to from the given pointers in the
index. Maybe it
would be worthwhile to scrape the whole mess and have it in
searchable
text form. Another thing Python would be the right tool for the job
for. Regular updates as the docs are updated would be a good
idea too.
It's obvious that today's Google isn't up to it, although it
occurs to
me that I haven't tried Google's site search on python.org.
On Windows, the (at least, for ActiveState releases)
documentation is available in Windows Help format -- though
I'll admit the "free text search" leaves a lot to be desired...
"dict comprehension" didn't find anything obvious;
"dictionary comprehension" brought up PEP 274 (note: I still
use 2.7 as main version).
-=-=-=-=-=-
Semantics
The semantics of dict comprehensions can actually be demonstrated
in stock Python 2.2, by passing a list comprehension to the
builtin dictionary constructor:
>>> dict([(i, chr(65+i)) for i in range(4)])
is semantically equivalent to
>>> {i : chr(65+i) for i in range(4)}
The dictionary constructor approach has two dictinct disadvantages
from the proposed syntax though. First, it isn't as legible as a
dict comprehension. Second, it forces the programmer to create an
in-core list object first, which could be expensive.
-=-=-=-=-=-
--
Wulfraed Dennis Lee Bieber AF6VN
wlfr...@ix.netcom.com HTTP://wlfraed.home.netcom.com/
It would be interesting to play around with different list
comprehensions than the one they've shown.
I'll admit that both dictionaries and comprehensions are still a little
bit fuzzy to me, especially when I get away from the common usages. This
could be a good exercise to clarify some of the fuzzy areas.
Deborah
And don't forget
dict_comp : { k:v for (k,v) in kv_provider }
set_comp : { item for item in item_provider }
set_of_tuples_comp : { (k,v) for (k,v) in kv_provider }
Just to make things more complicated.
--
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order. See above to fix.
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