Re: yield from () Was: Re: weirdness with list()

[Thomas Jollans]

On 03/03/2021 01:01, Cameron Simpson wrote:

On 02Mar2021 15:06, Larry Martell  wrote:

I discovered something new (to me) yesterday. Was writing a unit test
for generator function and I found that none of the function got
executed at all until I iterated on the return value.

Aye. Generators are lazy - they don't run at all until you ask for a
value.

By contrast, this is unlike Go's goroutines, which are busy - they
commence operation as soon as invoked and run until the first yield
(channel put, I forget how it is spelled now). This can cause excessive
CPU utilisation, but it handle for _fast_ production of results. Which
is a primary goal in Go's design.

Cheers,
Cameron Simpson 




I've been learning a bit more JavaScript recently (I know, I know, 
that's no fun) and I think that's the main practical difference between 
JavaScript's async functions, which are scheduled even if nobody awaits 
on them, and Python async functions which are just funky generators and 
therefore scheduled only when somebody awaits their result.




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Re: Why assert is not a function?

[Richard Damon]

On 3/12/21 12:31 AM, Chris Angelico wrote:
> On Fri, Mar 12, 2021 at 3:53 PM Cameron Simpson  wrote:
>> For me, try/except is for when something might reasonably "go wrong" in
>> normal use, even niche normal use. Whereas assert is for things which
>> should _never_ occur. Roughly, again for me, try/except if for catching
>> misuse and assert is for catching misdesign/misimplementation.
> Something like that, yeah. An assertion failure represents a bug *in
> this code*, something that shouldn't ever happen. If it's possible to
> trigger the failure with some other piece of code (calling something
> with bad arguments, or whatever), then assert is the wrong tool for
> the job. Similarly, if you find yourself catching AssertionError
> anywhere outside of unit testing, something is horribly wrong
> somewhere :)
>
> ChrisA

Chris, I would disagree with that statement. An assert says that there
is something wrong with THE code, not THIS code. It is perfectly
reasonable, and good defensive programming, to assert on the
per-conditions to the procedure at its beginning.

Now, it may be true that a 'friendlier' procedure may be defined to
check some of these and return an error, but that then locks that
behavior into the API, so the cost of the check becomes an absolute
requirement.

In langauges like C, the assert for this may be more important because
the language provides more opportunity for 'undefined behavior'.

It is reasonable to skip the input assert if it becomes too expensive
for benefit it provides, or if something else will catch the error. This
likely actually applies to a lot of Python code, so it may seem that it
doesn't apply.

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<< robot control >>

[Alex Kaye]

I am looking for a package or module that

would use my Rasberry Pi 3 wirelessly to control a

land vehicle or someone to consult with to

discuss some of my options. Maybe with joystick commands.


Alex
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Re: Why assert is not a function?

[Chris Angelico]

On Sat, Mar 13, 2021 at 12:11 AM Richard Damon  wrote:
>
> On 3/12/21 12:31 AM, Chris Angelico wrote:
> > On Fri, Mar 12, 2021 at 3:53 PM Cameron Simpson  wrote:
> >> For me, try/except is for when something might reasonably "go wrong" in
> >> normal use, even niche normal use. Whereas assert is for things which
> >> should _never_ occur. Roughly, again for me, try/except if for catching
> >> misuse and assert is for catching misdesign/misimplementation.
> > Something like that, yeah. An assertion failure represents a bug *in
> > this code*, something that shouldn't ever happen. If it's possible to
> > trigger the failure with some other piece of code (calling something
> > with bad arguments, or whatever), then assert is the wrong tool for
> > the job. Similarly, if you find yourself catching AssertionError
> > anywhere outside of unit testing, something is horribly wrong
> > somewhere :)
> >
> > ChrisA
>
> Chris, I would disagree with that statement. An assert says that there
> is something wrong with THE code, not THIS code. It is perfectly
> reasonable, and good defensive programming, to assert on the
> per-conditions to the procedure at its beginning.
>
> Now, it may be true that a 'friendlier' procedure may be defined to
> check some of these and return an error, but that then locks that
> behavior into the API, so the cost of the check becomes an absolute
> requirement.
>

It's perfectly reasonable to put "if condition: raise Blah", but is it
really reasonable to use the assert statement, which (a) might not be
run, and (b) raises a very generic exception? Make assertions about
your own code, not other people's.

ChrisA
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Re: Why assert is not a function?

[Marco Sulla]

On Thu, 11 Mar 2021 at 23:11, Ethan Furman  wrote:
> Basically, you are looking at two different philosophies:
>
> - Always double check, get good error message when something fails
>
> vs
>
> - check during testing and QA, turn off double-checks for production for best 
> performance possible.

In a perfect world, I said the second option is the best. But for the
majority of projects I contributed, speed was not a critical issue. On
the contrary, it's very hard to get meaningful informations about
problems in production, so I'm in favour of the first school :)
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Scientific Software Developer | Job position at CMCC Foundation, Italy

[info cmcc]

*Please, feel free to circulate *
*to anyone you think may be interested.**---*

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The minimum qualifications are:

   - M.Sc. degree in Computer Science or Computer Engineering or equivalent
   fields;
   - 2+ years experience in scientific software development;
   - Excellent knowledge of Python programming languages;
   - Good knowledge of Python scientific libraries (numpy, scipy,pandas);
   - Excellent knowledge of Git;
   - Good knowledge of container technologies (Docker, Kubernetes);
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Via Augusto Imperatore, 16 - 73100 Lecce
i...@cmcc.it - www.cmcc.it
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Uninstall error

[Premmy]

Hi. I am trying to uninstall python on my computer because i found a better
one but its not getting deleted from control panel. can you please help me

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Mobile: 07502069339
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pygame "font not intialized"

[Quentin Bock]

my code is almost identical to this so I hope it's okay that I don't
include all of my code
error message:
font = pygame.font.Font('freesansbold.ttf', 32)
pygame.error: font not initialized

Tutorial Link: https://www.youtube.com/watch?v=FfWpgLFMI7w
Timestamp to this part of the video:  1:55:08
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Re: pygame "font not intialized"

[2QdxY4RzWzUUiLuE]

On 2021-03-12 at 17:27:36 -0500,
Quentin Bock  wrote:

> my code is almost identical to this so I hope it's okay that I don't
> include all of my code
> error message:
> font = pygame.font.Font('freesansbold.ttf', 32)
> pygame.error: font not initialized
> 
> Tutorial Link: https://www.youtube.com/watch?v=FfWpgLFMI7w
> Timestamp to this part of the video:  1:55:08

https://duckduckgo.com/?q=pygame.error%3A+font+not+initialized

See also .
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