Subject: Re: Is there a better way? [combining f-string, thousands separator,
right align]

On 2024-08-25 16:12, Gilmeh Serda via Python-list wrote:

Subject explains it, or ask.

This is a bloody mess:

s = "123456789" # arrives as str
f"{f'{int(s):,}': >20}"

' 123,456,789'

You don't need to format twice; you can combine them:

s = "123456789"
f'{int(s): >20,}'

' 123,456,789'

or if you rely on default behaviour:

f'{int(s):20,}'

' 123,456,789'


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Subject: Re: Is there a better way? [combining f-string, thousands separator,
right align]

On 26/08/24 03:12, Gilmeh Serda via Python-list wrote:

Subject explains it, or ask.

This is a bloody mess:

s = "123456789" # arrives as str
f"{f'{int(s):,}': >20}"

' 123,456,789'

With recent improvements to the expressions within F-strings, we can
separate the string from the format required. (reminiscent of FORTRAN
which had both WRITE and FORMAT statements, or for that matter HTML
which states the 'what' and CSS the 'how')

Given that the int() instance-creation has a higher likelihood of
data-error, it is recommended that it be a separate operation for ease
of fault-finding - indeed some will want to wrap it with try...except.

s = "123456789" # arrives as str
s_int = int( s ) # makes the transformation obvious and distinct

s_format = ">20," # define how the value should be presented

F"{s_int:{s_format}}"

' 123,456,789'


Further, some of us don't like 'magic-constants', hence (previously):

S_FIELD_WIDTH = 20
s_format = F">{S_FIELD_WIDTH},"

and if we really want to go over-board:

RIGHT_JUSTIFIED = ">"
THOUSANDS_SEPARATOR = ","
s_format = F"{RIGHT_JUSTIFIED}{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

or (better) because right-justification is the default for numbers:

s_format = F"{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

To the extreme that if your user keeps fiddling with presentations (none
ever do, do they?), all settings to do with s_format could be added to a config/environment file, and thus be even further separated from program-logic!

--
Regards,
=dn

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Subject: Re: Is there a better way? [combining f-string, thousands separator,
right align]

On 2024-08-26 at 20:42:32 +1200,
dn via Python-list <python-list@python.org> wrote:

and if we really want to go over-board:

RIGHT_JUSTIFIED = ">"
THOUSANDS_SEPARATOR = ","
s_format = F"{RIGHT_JUSTIFIED}{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

or (better) because right-justification is the default for numbers:

s_format = F"{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

To the extreme that if your user keeps fiddling with presentations (none
ever do, do they?), all settings to do with s_format could be added to a config/environment file, and thus be even further separated from program-logic!

And then you'll need a parser, many of whose Unique Challenges™ aren't
even apparent until you start parsing files from actual users, and
you'll still need some sort of fallback in the code anyway for the case
that s_format can't be parsed (for whatever reason).

Isn't a config file what just caused the global CrowdStrike outage? ;-)

That said, I understand that report generators are a thing, not to
mention RPG (https://en.wikipedia.org/wiki/IBM_RPG).

Okay, sorry; I'll just crawl back into the hole from whence I came.

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Subject: Re: Is there a better way? [combining f-string, thousands separator,
right align]

On 26/08/24 23:00, Dan Sommers via Python-list wrote:

On 2024-08-26 at 20:42:32 +1200,
dn via Python-list <python-list@python.org> wrote:

and if we really want to go over-board:

RIGHT_JUSTIFIED = ">"
THOUSANDS_SEPARATOR = ","
s_format = F"{RIGHT_JUSTIFIED}{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

or (better) because right-justification is the default for numbers:

s_format = F"{S_FIELD_WIDTH}{THOUSANDS_SEPARATOR}"

To the extreme that if your user keeps fiddling with presentations (none
ever do, do they?), all settings to do with s_format could be added to a
config/environment file, and thus be even further separated from
program-logic!

And then you'll need a parser, many of whose Unique Challenges™ aren't
even apparent until you start parsing files from actual users, and
you'll still need some sort of fallback in the code anyway for the case
that s_format can't be parsed (for whatever reason).

Isn't a config file what just caused the global CrowdStrike outage? ;-)

That said, I understand that report generators are a thing, not to
mention RPG (https://en.wikipedia.org/wiki/IBM_RPG).

Okay, sorry; I'll just crawl back into the hole from whence I came.

Not at all. Please continue to question/ask/suggest!

This is a valid point. There are costs and benefits (trade-offs) to all decisions!

That said, writing one's own parser would become a veritable can of worms/rabbit hole. Here be dragons!

Similarly, explaining this takes longer than writing the example itself!


Older Windows users will know about .ini files, and Linux Admins are
familiar with .conf files. Many of us are already using JSON or YAML
formats. Any of these (and more) could be pressed into service, as
above. At the 'top end', there are also whole libraries devoted to establishing application configuration or "environments": default
values, config files, command-line options, user-input...

Have switched to using Python-poetry, which replaces packaging methods
such as setuptools (as well as virtual-environment tools). It takes its project configuration specifications from a pyproject.toml file. So, for
a few projects lately, I've been using .toml for application-config as
well. However, I have to say, this more from an attempt at consistency
than a decision of logic. (critique welcome)

That said, a setup.py configuration, took the form:

setup(
name='demo_project',
version='1.1.0',
packages=find_packages(),
install_requires=[
'requests',
'numpy',
...
],
entry_points={
....

Accordingly, it offers an example of the simplest format (for us), and
one which has a zero-learning pre-requisite. At execution-time, the
moment such a config is import-ed, a syntax-error will immediately bring proceedings to a halt!


I have some stats-wonks as clients. They dabble in programming, but (fortunately) realise their limitations. (usually!) The boss has had to
ban them from 'improving' my code ($paid to be an improvement on their
usual quality), but including a .py configuration/options file has
proven to be an honor-preserving compromise. Of course, they manage
their own runs, adjusting parameters as they go. So, any errors are
their own, and they can fix themselves (without anyone else knowing!).

Such would not work in many?most other environments - children: do not
try this at home!


An irritation for those of us who have to delve into projects after
they've been written, is a git-history full of the sorts of
user-tweaking changes vilified earlier. Putting user-config into a
separate file, even a separate sub-directory, makes it easy to spot
which updates to ignore, and thus, which to consider!


PS the reason why CrowdStrike was not the end of humanity as we know it,
(and only that of those who only know MSFT's eco-system) is because the majority of the world's Internet servers run Linux - including Azure
(brings to mind the old saw: the package said "runs on Windows-95 or
better" so I installed it on Linux!)

Joking aside, we (virtuous ones) ALWAYS test BEFORE release. Correct?

--
Regards,
=dn

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