[Python-Dev] (no subject)

[Victor Stinner]

Le 10 févr. 2015 06:48, "Greg Ewing" <greg.ewing at canterbury.ac.nz> a écrit :
> It could potentially be a little more efficient by
> eliminating the construction of an intermediate list.

Is it the case in the implementation? If it has to create a temporary
list/tuple, I will prefer to not use it.

After long years of development, I chose to limit myself to one instruction
per line. It is for different reason:
- I spend more time to read code than to write code, readability matters
- it's easier to debug: most debugger work line by line, or at least it's a
convinient way to use them. If you use instruction per instruction, usually
you have to read assember/bytecode to get the current instruction
- profilers computes statistics per line,not per instruction (it's also the
case for tracemalloc)
- tracebacks only give the line number, not the column
- etc.

So I now prefer more verbise code even it is longer to write and may look
less efficient.

> Same again, multiple ** avoids construction of an
> itermediate dict.

Again, is it the case in the implementation. It may be possible to modify
CPython to really avoid a temporary dict (at least for some kind of Python
functions), but it would a large refactoring.

Usually, if an operation is not efficient, it's not implement, so users
don't try to use it and may even try to write their code differently (to
avoid the performance issue).

(But slow operations exist like list.remove.)

Victor
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