gh-131236: allow to generate multiple UUIDs at once via CLI by simon04 · Pull Request #131218 · python/cpython · GitHub

Fixes #131236.

Add --count to the main() of the uuid module.

Sometimes you need more than one UUID. In order to print 42 UUIDs, run python -m uuid --count 42

Inspired by https://www.man7.org/linux/man-pages/man1/uuidgen.1.html

📚 Documentation preview 📚: https://cpython-previews--131218.org.readthedocs.build/

Issue: Allow to generate multiple UUIDs at once via CLI #131236

Sometimes you need more than one UUID. Inspired by https://www.man7.org/linux/man-pages/man1/uuidgen.1.html

Thank you for idea, but we usually open issue before adding any feature.

Contribution process is documented here: https://devguide.python.org/

Suggested change

      
                                    help="Generate more uuids in loop. ")
          
                                    help="Generate COUNT UUIDs. Default: 1.")

Or add formatter_class=argparse.ArgumentDefaultsHelpFormatter to argparse.ArgumentParser() and:

Suggested change

      
                                    help="Generate more uuids in loop. ")
          
                                    help="Generate this many UUIDs.")

And also delete "By default uuid4 function is used."

I would like to have a short option -C as well so to mimick uuidgen, and use NUM as a metavar instead of COUNT. In addition, we can just say Generate NUM fresh UUIDs

And also delete "By default uuid4 function is used."

Isn't it the default though?

Yes, but argparse.ArgumentDefaultsHelpFormatter prints the default for us:

❯ ./python.exe -m uuid -h
usage: python.exe -m uuid [-h]
                          [-u {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}]
                          [-n NAMESPACE] [-N NAME] [--count COUNT]

Generates a uuid using the selected uuid function.

options:
  -h, --help            show this help message and exit
  -u, --uuid {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}
                        The function to use to generate the uuid. By default
                        uuid4 function is used. (default: uuid4)
  -n, --namespace NAMESPACE
                        The namespace is a UUID, or '@ns' where 'ns' is a
                        well-known predefined UUID addressed by namespace
                        name. Such as @dns, @url, @oid, and @x500. Only
                        required for uuid3/uuid5 functions. (default: None)
  -N, --name NAME       The name used as part of generating the uuid. Only
                        required for uuid3/uuid5 functions. (default: None)
  --count COUNT         Generate more uuids in loop. (default: 1)

(I have an idea to add colour to those in future.)

Oh. I thought that the suggestion was separate, my bad

With ArgumentDefaultsHelpFormatter it would look the following:

It seems that the typesetting of the help text mixed – Do we start the help text with a capital letter? Do we use a period at the end (this looks strange with the (default: 1) generated by ArgumentDefaultsHelpFormatter)?

> python -m uuid -h
usage: python -m uuid [-h] [-u {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}] [-n NAMESPACE] [-N NAME] [-C NUM]

Generates a uuid using the selected uuid function.

options:
  -h, --help            show this help message and exit
  -u, --uuid {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}
                        The function to use to generate the uuid. (default: uuid4)
  -n, --namespace NAMESPACE
                        The namespace is a UUID, or '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name. Such as @dns, @url, @oid, and @x500. Only required
                        for uuid3/uuid5 functions. (default: None)
  -N, --name NAME       The name used as part of generating the uuid. Only required for uuid3/uuid5 functions. (default: None)
  -C, --count NUM       Generate NUM fresh UUIDs. (default: 1)

Adding ArgumentDefaultsHelpFormatter, going for lowercase first letter, removing period at the end, adding metavar="NS" for namespace yields a more compact and consistent help output:

> python -m uuid -h
usage: python -m uuid [-h] [-u {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}] [-n NS] [-N NAME] [-C NUM]

Generate a UUID using the selected UUID function.

options:
  -h, --help            show this help message and exit
  -u, --uuid {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}
                        function to generate the UUID (default: uuid4)
  -n, --namespace NS    a UUID, or '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name, such as @dns, @url, @oid, and @x500 (only required for uuid3/uuid5)
                        (default: None)
  -N, --name NAME       name used as part of generating the UUID (only required for uuid3/uuid5) (default: None)
  -C, --count NUM       generate NUM fresh UUIDs (default: 1)

I'm still not happy with the verbose --namespace help, though:

  -n, --namespace NS    a UUID, or '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name, such as @dns, @url, @oid, and @x500 (only required for uuid3/uuid5)
                        (default: None)

Is the following any better?

  -n, --namespace NS    a UUID, or @dns, @url, @oid, @x500, or any '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name (only required for uuid3/uuid5)
                        (default: None)

Or specify the few choices explicitly?

  -n, --namespace {any UUID,@dns,@url,@oid,@x500}
                        a UUID, or a well-known predefined UUID addressed by namespace name (only required for uuid3/uuid5) (default: None)

Adding ArgumentDefaultsHelpFormatter, going for lowercase first letter, removing period at the end, adding metavar="NS" for namespace yields a more compact and consistent help output:

👍

I'm still not happy with the very verbose "a UUID, or '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name, such as @dns, @url, @oid, and @x500 (only required for uuid3/uuid5)", though. Is "a UUID, or @dns, @url, @oid, @x500, or any '@ns' where 'ns' is a well-known predefined UUID addressed by namespace name (only required for uuid3/uuid5)" any better?

It's a bit better, and I don't have a much better suggestion :)

I think we could also prefix and shorten the "(only required for uuid3/uuid5)" bits, so if you're not using uuid3/5 you can immediately skip it and save some mental effort:

  -n, --namespace NS    uuid3/uuid5 only: [etc]
                        (default: None)
  -N, --name NAME       uuid3/uuid5 only: name used as part of generating the UUID (default: None)

For --namespace, maybe specify the few choices explicitly?

  -n, --namespace {any UUID,@dns,@url,@oid,@x500}
                        uuid3/uuid5 only: a UUID, or a well-known predefined UUID addressed by namespace name (default: None)

Thanks for your ideas. Here's the concise result:

> python -m uuid -h
usage: python -m uuid [-h] [-u {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}] [-n {any UUID,@dns,@url,@oid,@x500}] [-N NAME] [-C NUM]

Generate a UUID using the selected UUID function.

options:
  -h, --help            show this help message and exit
  -u, --uuid {uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}
                        function to generate the UUID (default: uuid4)
  -n, --namespace {any UUID,@dns,@url,@oid,@x500}
                        uuid3/uuid5 only: a UUID, or a well-known predefined UUID addressed by namespace name) (default: None)
  -N, --name NAME       uuid3/uuid5 only: name used as part of generating the UUID (default: None)
  -C, --count NUM       generate NUM fresh UUIDs (default: 1)

As mentioned, please open an issue, and add a NEWS file.

cc @picnixz

I would like to have a short option -C as well so to mimick uuidgen, and use NUM as a metavar instead of COUNT. In addition, we can just say Generate NUM fresh UUIDs

And also delete "By default uuid4 function is used."

Isn't it the default though?

We also need some What's New entry. The uuid module is an old module that didn't have lots of updates these past 10 years so not everyone may remember that the CLI exists. Since we also improved quite significantly this module these past months, it's good to highlight the new features.

Hi all, thank you for the feedback. I've created an issue, created a news entry, updated the help text to "Generate NUM fresh UUIDs.", added -c, added metavar "NUM".

Do we have tests for the CLI? if yes, please update them, otherwise let's add them in a follow-up PR.

Sorry, it is not clear for me, what's your use-case. You can already generate any amount of uuids as simple as:

» for i in {1..4} ; do ./python.exe -m uuid ; done
11afb3ee-2e62-4e7f-93d2-e073cd44b093
4ebad66f-a4b2-4f5e-b34a-2bfbdc6db7ac
d8068024-d316-4ccd-bfae-ded9c3f5c504
400a0201-5fe1-4868-895d-9db6d3288e5c

Basically, all shells support loops.

…jqFq0.rst Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Sorry, it is not clear for me, what's your use-case.

@sobolevn, invoking 100 Python interpreters on Windows via Git Bash (MINGW64) takes 13s when it could complete in 0.102s

MINGW64$ time sh -c 'seq 100 | xargs -i python.exe -m uuid'
real    0m12.974s
user    0m0.090s
sys     0m0.363s

MINGW64$ time python.exe -c 'import uuid
for _ in range(100):
    print(uuid.uuid4())
'
real    0m0.102s
user    0m0.000s
sys     0m0.015s

Do we have tests for the CLI?

@picnixz, thank you for your review. I've added a CLI test test_cli_uuid4_outputted_with_count.

@simon04 thanks, these numbers make sense to me!

@simon04 Tip: there's usually no need to click the "Update branch" button:

https://devguide.python.org/getting-started/pull-request-lifecycle/#update-branch-button

Thanks!

Thank you!

Something else I noticed, but this can be a followup PR. The docs start with:

library reference
"Command-Line Usage"
library "Example"
"Command-Line Example"

Let's restructure (and use sentence case):

library reference
library "Example"
"Command-line usage"
"Command-line example"

…thon#131218) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

uuid: add --count to main

f2775cb

Sometimes you need more than one UUID. Inspired by https://www.man7.org/linux/man-pages/man1/uuidgen.1.html

bedevere-app Bot added the awaiting review label Mar 14, 2025

hugovk reviewed Mar 14, 2025

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picnixz reviewed Mar 14, 2025

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simon04 added 2 commits March 14, 2025 12:22

Add news

ff6dc1c

"Generate NUM fresh UUIDs."

0f95b45

picnixz changed the title uuid: add --count to main gh-131236: allow to generate multiple UUIDs at once via CLI Mar 14, 2025

bedevere-app Bot mentioned this pull request Mar 14, 2025

Allow to generate multiple UUIDs at once via CLI #131236

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simon04 and others added 7 commits March 14, 2025 13:06

Update Misc/NEWS.d/next/Library/2025-03-14-12-22-02.gh-issue-131236.H…

8ec7c36

…jqFq0.rst Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Update Doc/library/uuid.rst

13c3428

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Update Lib/uuid.py

6535ead

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

"UUID"

e34e8b4

uuid -C

3cab8b2

test_cli_uuid4_outputted_with_count

5b5f34a

Add 3.14 news

4577a99

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simon04 added 2 commits March 14, 2025 13:24

Add 3.14 news

6ea8b3a

Add 3.14 news

206caad

Merge branch 'main' into uuid-count

038bfbb

simon04 added 5 commits March 14, 2025 16:34

"UUID"

b3ef5e6

ArgumentDefaultsHelpFormatter

33f7cd1

namespace

43ee1ab

namespace

e7c214f

namespace

1a6ad78

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wrap lines

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wrap lines

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hugovk approved these changes Mar 17, 2025

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hugovk merged commit 52b5eb9 into python:main Mar 26, 2025

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diegorusso pushed a commit to diegorusso/cpython that referenced this pull request Apr 1, 2025

pythongh-131236 : allow to generate multiple UUIDs at once via CLI (py…

ac167c9

…thon#131218) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

                                       help="The name used as part of generating the uuid. "
                                       "Only required for uuid3/uuid5 functions.")
+                  parser.add_argument("--count", type=int, default=1,
+                                      help="Generate more uuids in loop. ")

                                       help="The name used as part of generating the uuid. "
                                       "Only required for uuid3/uuid5 functions.")
+                  parser.add_argument("--count", type=int, default=1,
+                                      help="Generate more uuids in loop. ")

                                       help="The name used as part of generating the uuid. "
                                       "Only required for uuid3/uuid5 functions.")
+                  parser.add_argument("--count", type=int, default=1,
+                                      help="Generate more uuids in loop. ")

	help="Generate more uuids in loop. ")
	help="Generate COUNT UUIDs. Default: 1.")

	help="Generate more uuids in loop. ")
	help="Generate this many UUIDs.")

gh-131236: allow to generate multiple UUIDs at once via CLI by simon04 · Pull Request #131218 · python/cpython · GitHub

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gh-131236: allow to generate multiple UUIDs at once via CLI - #131218

gh-131236: allow to generate multiple UUIDs at once via CLI#131218hugovk merged 20 commits intopython:mainpython/cpython:mainfrom simon04:uuid-countsimon04/cpython:uuid-countCopy head branch name to clipboard

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gh-131236: allow to generate multiple UUIDs at once via CLI#131218
hugovk merged 20 commits into
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