Re: [Python-Dev] Deprecating float.is_integer()

Here's an excerpted (and slightly simplified for consumption here) usage of float.is_integer() from the top of a function which does some convolution/filtering in a geophysics application. I've mostly seen it used in guard clauses in this way to reject either illegal numeric arguments directly, or

Re: [Python-Dev] ThreadedProcessPoolExecutor

El mié., 21 mar. 2018 a las 16:23, Guido van Rossum () escribió: > Roberto, > > That looks like an interesting class. I presume you're intending to > publish this as a pip package on PyPI.python.org? > > Precisely. I'm no lawyer, but I believe you can license your code under a

Re: [Python-Dev] Deprecating float.is_integer()

On Wed, Mar 21, 2018 at 3:02 PM, Tim Peters wrote: > [David Mertz] > > I've been using and teaching python for close to 20 years and I never > > noticed that x.is_integer() exists until this thread. > > Except it was impossible to notice across most of those years, because

Re: [Python-Dev] Deprecating float.is_integer()

On Wed, Mar 21, 2018 at 11:14 AM, David Mertz wrote: > I've been using and teaching python for close to 20 years and I never > noticed that x.is_integer() exists until this thread. I would say the "one > obvious way" is less than obvious. > > On the other hand, `x == int(x)` is

Re: [Python-Dev] Deprecating float.is_integer()

[David Mertz] > I've been using and teaching python for close to 20 years and I never > noticed that x.is_integer() exists until this thread. Except it was impossible to notice across most of those years, because it didn't exist across most of those years ;-) > I would say the "one obvious way"

Re: [Python-Dev] Deprecating float.is_integer()

I'd prefer to see `float.is_integer` stay. There _are_ occasions when one wants to check that a floating-point number is integral, and on those occasions, using `x.is_integer()` is the one obvious way to do it. I don't think the fact that it can be misused should be grounds for deprecation. As

Re: [Python-Dev] Deprecating float.is_integer()

I've been using and teaching python for close to 20 years and I never noticed that x.is_integer() exists until this thread. I would say the "one obvious way" is less than obvious. On the other hand, `x == int(x)` is genuinely obvious... and it immediately suggests the probably better

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 4:42 AM Steven D'Aprano wrote: > > > > Could float et al. add an __index__ method that would return a ValueError > > if the value was not an integer? > > That would allow us to write things like: > > "abcdefgh"[5.0] > > which is one of the things

[Python-Dev] What is the purpose of NEXT_BLOCK()?

There is the NEXT_BLOCK() macro in compile.c. It creates a new block, creates an implicit jump from the current block to the new block, and sets it as the current block. But why it is used? All seems working if remove NEXT_BLOCK(). If there was a need of NEXT_BLOCK() (if it reduces the

Re: [Python-Dev] Deprecating float.is_integer()

> > > Does anybody know examples of the correct use of float.is_integer() in > real programs? For now it looks just like a bug magnet. I suggest to > deprecate it in 3.7 or 3.8 and remove in 3.9 or 3.10. +1 It really doesn’t appear to be the right solution for any problem. -CHB --

[Python-Dev] Deprecating float.is_integer()

I searched usages of is_integer() on GitHub and have found that it is used *only* in silly code like (x/5).is_integer(), (x**0.5).is_integer() (or even (x**(1/3)).is_integer()) and in loops like: i = 0 while i < 20: if i.is_integer(): print(i) i += 0.1

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 10:31:19AM +, Chris Barker wrote: > On Wed, Mar 21, 2018 at 4:42 AM Steven D'Aprano wrote: > > > Could float et al. add an __index__ method that would return a ValueError > > > if the value was not an integer? > > > > That would allow us to write

Re: [Python-Dev] Symmetry arguments for API expansion

On 14 March 2018 at 08:29, Tim Peters wrote: > [Tim] > >> An obvious way to extend it is for Fraction() to look for a special > >> method too, say "_as_integer_ratio()". > > [Greg Ewing] > > Why not __as_integer_ratio__? > > Because. at this point, that would be beating a

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 09:46:06AM -0700, Nathaniel Smith wrote: [...] > For me this is an argument against is_integer() rather than for it :-). > is_prime(float) should *obviously*[1] be a TypeError. Primality is only > meaningfully defined over the domain of integers And 3.0 is an integer. Just

Re: [Python-Dev] Deprecating float.is_integer()

Note: this is a top-posted essay much more about floating-point philosophy than about details. Details follow from the philosophy, and if philosophies don't match the desired details will never match either. Understanding floating point requires accepting that they're a funky subset of rational

Re: [Python-Dev] Deprecating float.is_integer()

On Wed, Mar 21, 2018 at 8:49 PM, David Mertz wrote: > For example, this can be true (even without reaching inf): > > >>> x.is_integer() > True > >>> (math.sqrt(x**2)).is_integer() > False > If you have a moment to share it, I'd be interested to know what value of `x` you used

Re: [Python-Dev] What is the purpose of NEXT_BLOCK()?

Maybe spelunking in the Python 2 branch will help? It seems it was introduced in 2005 by Jeremy Hylton with this comment: /* The distinction between NEW_BLOCK and NEXT_BLOCK is subtle. (I'd like to find better names.) NEW_BLOCK() creates a new block and sets it as the current block.

Re: [Python-Dev] Deprecating float.is_integer()

I searched 6M LoC of Python code at Dropbox and found only three uses. They seem legit. Two are about formatting a number that's given as a float, deciding whether to print a float as 42 or 3.14. The third is attempting a conversion from float to integer where a non-integer must raise a specific

[Python-Dev] ThreadedProcessPoolExecutor

Hi, I've made a custom concurrent.futures.Executor mixing the ProcessPoolExecutor and ThreadPoolExecutor. I've published it here: https://github.com/nilp0inter/threadedprocess This executor is very similar to a ProcessPoolExecutor, but each process in the pool have it's own ThreadPoolExecutor

Re: [Python-Dev] Deprecating float.is_integer()

> [Mark Dickinson ] >> If you have a moment to share it, I'd be interested to know what value of >> `x` you used to achieve this, and what system you were on. This can't happen >> under IEEE 754 arithmetic. > > I expect it might happen under one of the directed rounding modes

Re: [Python-Dev] Deprecating float.is_integer()

[Devin Jeanpierre ] > PyPy (5.8): > x = 1e300 > x.is_integer() > True > math.sqrt(x**2).is_integer() > False > x**2 > inf I think you missed that David said "even without reaching inf" (you did reach inf), and that I said "such that x*x neither

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 12:38 PM, Steven D'Aprano wrote: > In fact, Serhiy's suggestion is not correct when x is not a float: > This is a key point -- see some of Tim's posts -- like ot or not, you probably need to know when you are working with a float and when you aren't

Re: [Python-Dev] Deprecating float.is_integer()

OK, we'll keep float.is_integer(), and that's a pronouncement, so that we can hopefully end this thread soon. It should also be added to int. After all that's what started this thread, with the observation that mypy and PEP 484 consider an int valid whenever a float is expected. Since PEP 484

Re: [Python-Dev] Deprecating float.is_integer()

[David Mertz ] >> For example, this can be true (even without reaching inf): >> >> >>> x.is_integer() >> True >> >>> (math.sqrt(x**2)).is_integer() >> False [Mark Dickinson ] > If you have a moment to share it, I'd be interested to know what value of > `x`

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 4:12 PM, Guido van Rossum wrote: > Thank you! As you may or may not have noticed in a different thread, we're > going through a small existential crisis regarding the usefulness of > is_integer() -- Serhiy believes it is not useful (and even an

Re: [Python-Dev] Deprecating float.is_integer()

Ok. I'm wrong on that example. On Wed, Mar 21, 2018, 9:11 PM Tim Peters wrote: > [David Mertz ] > >> For example, this can be true (even without reaching inf): > >> > >> >>> x.is_integer() > >> True > >> >>> (math.sqrt(x**2)).is_integer() > >> False > >

Re: [Python-Dev] Symmetry arguments for API expansion

On Wed, Mar 21, 2018 at 6:48 PM, Chris Barker wrote: > On Wed, Mar 21, 2018 at 4:12 PM, Guido van Rossum > wrote: > >> Thank you! As you may or may not have noticed in a different thread, >> we're going through a small existential crisis regarding the

Re: [Python-Dev] Deprecating float.is_integer()

On Wed, Mar 21, 2018 at 11:43 PM, Tim Peters wrote: > Note: this is a top-posted essay much more about floating-point > philosophy than about details. Details follow from the philosophy, > and if philosophies don't match the desired details will never match > either. >

Re: [Python-Dev] Deprecating float.is_integer()

[Chris Barker ] > ... > ... "is it the "right" thing to do in most cases, when deployed by folks > that haven't thought deeply about floating point. Gimme a break ;-) Even people who _believe_ they've thought about floating point still litter the bug tracker with >>> .1 +

Re: [Python-Dev] Symmetry arguments for API expansion

Thank you! As you may or may not have noticed in a different thread, we're going through a small existential crisis regarding the usefulness of is_integer() -- Serhiy believes it is not useful (and even an attractive nuisance) and should be deprecated. OTOH the existence of dec_mpd_isinteger()

Re: [Python-Dev] What is the purpose of NEXT_BLOCK()?

21.03.18 17:13, Guido van Rossum пише: Maybe spelunking in the Python 2 branch will help? It seems it was introduced in 2005 by Jeremy Hylton with this comment: /* The distinction between NEW_BLOCK and NEXT_BLOCK is subtle.  (I'd    like to find better names.)  NEW_BLOCK() creates a new block

Re: [Python-Dev] Deprecating float.is_integer()

On Wed, Mar 21, 2018 at 3:08 PM, Guido van Rossum wrote: > I searched 6M LoC of Python code at Dropbox and found only three uses. > They seem legit. Two are about formatting a number that's given as a float, > deciding whether to print a float as 42 or 3.14. The third is

Re: [Python-Dev] ThreadedProcessPoolExecutor

Roberto, That looks like an interesting class. I presume you're intending to publish this as a pip package on PyPI.python.org? I'm no lawyer, but I believe you can license your code under a new license (I recommend BSD) as long as you keep a copy and a mention of the PSF license in your

Re: [Python-Dev] Symmetry arguments for API expansion

As requested on the bug tracker, I've submitted a pull request for is_integer() support on the other numeric types. https://github.com/python/cpython/pull/6121 These are the tactics I used to implement it: - float: is_integer() already exists, so no changes - int: return True - Real: return x

Re: [Python-Dev] Symmetry arguments for API expansion

On Mar 21, 2018 05:40, "Steven D'Aprano" wrote: I don't want to change the behaviour of pow(), but we shouldn't dismiss the possibility of some other numeric function wanting to treat values N.0 and N the same. Let's say, an is_prime(x) function that supports floats as well