Imports and dot-notation
Mats Wichmann
mats at wichmann.us
Thu Aug 10 10:45:31 EDT 2023
On 8/9/23 17:28, dn via Python-list wrote:
> Side note: Using "...import identifier, ..." does not save storage-space
> over "import module" (the whole module is imported regardless, IIRC),
> however it does form an "interface" and thus recommend leaning into the
> "Interface Segregation Principle", or as our InfoSec brethren would say
> 'the principle of least privilege'. Accordingly, prefer "from ... import
> ... as ...".
>
Attribute lookup has *some* cost. That is, finding "c" in the local
namespace is going to be a little quicker than "b.c", where Python finds
"b" in the local namespace and then finds its "c" attribute; that's then
a little quicker than "a.b.c", etc.
See all relevant commentary about premature optimisation, spending time
optimising the wrong things, etc. but there *are* cases where it
matters (c.f. a tight loop that will be run many many times)
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