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bumpver/README.md
Manuel Barkhau bcf3d88f47 bump v202010.1040-beta -> v202010.1041-beta
2020-10-05 19:43:36 +00:00

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<div align="center">
<p align="center">
<img alt="logo" src="https://gitlab.com/mbarkhau/pycalver/-/raw/master/pycalver1k2_128.png">
</p>
</div>
# [PyCalVer: Automatic Calendar Versioning][url_repo]
PyCalVer is a CLI-tool to search and replace version strings in your project files ([calver][url_calver_org], [semver][url_semver_org] or otherwise) .
[url_repo]: https://gitlab.com/mbarkhau/pycalver
[url_calver_org]: https://calver.org/
[url_semver_org]: https://semver.org/
Project/Repo:
[![MIT License][img_license]][url_license]
[![Supported Python Versions][img_pyversions]][url_pyversions]
[![PyCalVer v202010.1041-beta][img_version]][url_version]
[![PyPI Releases][img_pypi]][url_pypi]
[![PyPI Downloads][img_downloads]][url_downloads]
Code Quality/CI:
[![GitHub Build Status][img_github_build]][url_github_build]
[![GitLab Build Status][img_gitlab_build]][url_gitlab_build]
[![Type Checked with mypy][img_mypy]][url_mypy]
[![Code Coverage][img_codecov]][url_codecov]
[![Code Style: sjfmt][img_style]][url_style]
| Name | role | since | until |
|-------------------------------------|-------------------|---------|-------|
| Manuel Barkhau (mbarkhau@gmail.com) | author/maintainer | 2018-09 | - |
[img_github_build]: https://github.com/mbarkhau/pycalver/workflows/CI/badge.svg
[url_github_build]: https://github.com/mbarkhau/pycalver/actions?query=workflow%3ACI
[img_gitlab_build]: https://gitlab.com/mbarkhau/pycalver/badges/master/pipeline.svg
[url_gitlab_build]: https://gitlab.com/mbarkhau/pycalver/pipelines
[img_codecov]: https://gitlab.com/mbarkhau/pycalver/badges/master/coverage.svg
[url_codecov]: https://mbarkhau.gitlab.io/pycalver/cov
[img_license]: https://img.shields.io/badge/License-MIT-blue.svg
[url_license]: https://gitlab.com/mbarkhau/pycalver/blob/master/LICENSE
[img_mypy]: https://img.shields.io/badge/mypy-checked-green.svg
[url_mypy]: https://mbarkhau.gitlab.io/pycalver/mypycov
[img_style]: https://img.shields.io/badge/code%20style-%20sjfmt-f71.svg
[url_style]: https://gitlab.com/mbarkhau/straitjacket/
[img_downloads]: https://pepy.tech/badge/pycalver/month
[url_downloads]: https://pepy.tech/project/pycalver
[img_version]: https://img.shields.io/static/v1.svg?label=PyCalVer&message=v202010.1041-beta&color=blue
[url_version]: https://pypi.org/project/pycalver/
[img_pypi]: https://img.shields.io/badge/PyPI-wheels-green.svg
[url_pypi]: https://pypi.org/project/pycalver/#files
[img_pyversions]: https://img.shields.io/pypi/pyversions/pycalver.svg
[url_pyversions]: https://pypi.python.org/pypi/pycalver
<!--
To update the TOC:
$ pip install md-toc
$ md_toc -i gitlab README.md
-->
[](TOC)
- [Usage](#usage)
- [Configuration](#configuration)
- [Pattern Search and Replacement](#pattern-search-and-replacement)
- [Examples](#examples)
- [Version State](#version-state)
- [The Current Version](#the-current-version)
- [Bump It Up](#bump-it-up)
- [The PyCalVer Format](#the-pycalver-format)
- [Parsing](#parsing)
- [Incrementing Behaviour](#incrementing-behaviour)
- [Lexical Ids](#lexical-ids)
- [Semantics of PyCalVer](#semantics-of-pycalver)
- [Intentional Breaking Changes](#intentional-breaking-changes)
- [Costs and Benefits](#costs-and-benefits)
- [Unintentional Breaking Changes](#unintentional-breaking-changes)
- [Pinning is not a Panacea](#pinning-is-not-a-panacea)
- [Zeno's 1.0 and The Eternal Beta](#zeno-s-1-0-and-the-eternal-beta)
[](TOC)
## Usage
### Search and Replace
With PyCalVer, you only have to specify one `version_pattern` which is used both to search for version strings as well as to generate the replacement when you do `pycalver bump`. Compare this e.g. to `bumpversion` where you declare separate configurations for `parse` and `serialize`.
```
[bumpversion]
current_version = 1.alpha
parse = (?P<major>\d+)\.(?P<release>.*)
serialize =
{major}.{release}
{major}
```
A similar version schema with PyCalVer would be:
```
[pycalver]
current_version = 1.alpha
version_pattern = MAJOR.RELEASE
```
Similarly you must specify file specific search and replace strings.
```
[bumpversion:file:requirements.txt]
search = MyProject=={current_version}
replace = MyProject=={new_version}
```
The same with PyCalVer would be:
```
[pycalver:file_patterns]
requirements.txt
MyProject=={version}
```
The string `{version}` is a placeholder which references whatever you specified in your `version_pattern`.
You can also be explicit and write the expanded version yourself if you prefer:
```
[pycalver:file_patterns]
requirements.txt
MyProject==MAJOR.RELEASE
```
> You may be asking at this point, "what if I want to match `MAJOR.RELEASE` as a literal string?".
> Well, tough luck. Realistically speaking, this has not been an issue.
In other words, you don't specify regular expressions manually, they are generated for by PyCalVer based on the parts defined below. Everything except for a valid part (in all caps) is treated as literal text.
### Patterns/Parts
> These patterns are closely based on [calver.org][url_calver_org_scheme].
[url_calver_org_scheme]: https://calver.org/#scheme
| part | range / example(s) | comment |
|-----------|---------------------------|--------------------------------------------|
| `YYYY` | 2019, 2020... | Full year, based on `strftime('%Y')` |
| `YY` | 18, 19..99, 1, 2 | Short year, based on `int(strftime('%y'))` |
| `MM` | 9, 10, 11, 12 | Month, based on `int(strftime('%m'))` |
| `DD` | 1, 2, 3..31 | Day, based on `int(strftime('%d'))` |
| `MAJOR` | 0..9, 10..99, 100.. | `pycalver bump --major` |
| `MINOR` | 0..9, 10..99, 100.. | `pycalver bump --minor` |
| `PATCH` | 0..9, 10..99, 100.. | `pycalver bump --patch` |
| `RELEASE` | alpha, beta, rc, post | `--release=<tag>` |
| `PYTAG` | a, b, rc, post | `--release=<tag>` |
| `NUM` | 0, 1, 2... | `-r/--release-num` |
| `BUILD` | 1001, 1002 .. 1999, 22000 | build number (maintains lexical order) |
| `INC0` | 0, 1, 2... | 0-based auto incrementing number |
| `INC1` | 1, 2... | 1-based auto incrementing number |
The above are the most commonly used. The following are also available, but you should be aware of the [Normalization Caveats](#normalization-caveats) if you want to use them.
| part | range / example(s) | comment |
|--------|---------------------|----------------------------------------------|
| `Q` | 1, 2, 3, 4 | Quarter |
| `0Y` | 18, 19..99, 01, 02 | Short Year `strftime('%y')`(zero-padded) |
| `0M` | 09, 10, 11, 12 | Month `strftime('%m')` (zero-padded) |
| `0D` | 01, 02, 03..31 | Day `strftime('%d')` (zero-padded) |
| `JJJ` | 1,2,3..366 | Day of year `int(strftime('%j'))` |
| `00J` | 001, 002..366 | Day of year `strftime('%j')` (zero-padded) |
| `WW` | 0, 1, 2..52 | Week number¹ `int(strftime('%W'))` |
| `0W` | 00, 01, 02..52 | Week number¹ `strftime('%W')` (zero-padded) |
| `UU` | 0, 1, 2..52 | Week number² `int(strftime('%U'))` |
| `0U` | 00, 01, 02..52 | Week number² `strftime('%U')` (zero-padded) |
| `VV` | 1, 2..53 | Week number¹³ `int(strftime('%V'))` |
| `0V` | 01, 02..53 | Week number¹³ `strftime('%V')` (zero-padded) |
| `GGGG` | 2019, 2020... | `strftime("%G")` ISO 8601 week-based year |
| `GG` | 19, 20...99, 0, 1 | Short ISO 8601 week-based year |
| `0G` | 19, 20...99, 00, 01 | Zero-padded ISO 8601 week-based year |
- ¹ Monday is the first day of the week.
- ² Sunday is the first day of the week.
- ³ ISO 8601 week. Week 1 contains Jan 4th.
> On Week Numbering
>
> Week numbering is a bit special, as it depends on your definition of "week":
>
> - Does it start on a Monday or a Sunday?
> - Range from 0-52 or 1-53 ?
> - At the beginning/end of the year, do you have partial weeks or do
> you have a week that span mutliple years?
> - If a week spans multiple years, what is the year number?
>
> If you use `VV`/`0V`, be aware that you cannot also use `YYYY`.
> Instead use `GGGG`. This is to avoid an edge case where your version
> number would run backwards if it was created around New Year.
### Rollover
TODO
### Configuration
The fastest way to setup a project is to use `pycalver init`.
```shell
$ pip install pycalver
...
Installing collected packages: click pathlib2 typing toml pycalver
Successfully installed pycalver-202010.1041b0
$ cd myproject
~/myproject/
$ pycalver init --dry
WARNING - File not found: pycalver.toml
Exiting because of '-d/--dry'. Would have written to pycalver.toml:
[pycalver]
current_version = "v202010.1001-alpha"
version_pattern = "vYYYY0M.BUILD[-RELEASE]"
commit_message = "bump version to {new_version}"
commit = true
tag = true
push = true
[pycalver.file_patterns]
"README.md" = [
"{version}",
"{pep440_version}",
]
"pycalver.toml" = [
'current_version = "{version}"',
]
```
If you already have a `setup.cfg` file, the `init` sub-command will
write to that instead.
```
~/myproject
$ ls
README.md setup.cfg setup.py
~/myproject
$ pycalver init
WARNING - Couldn't parse setup.cfg: Missing [pycalver] section.
Updated setup.cfg
```
This will add the something like the following to your `setup.cfg`
(depending on what files already exist in your project):
```ini
# setup.cfg
[pycalver]
current_version = "v201902.1001-alpha"
version_pattern = "vYYYY0M.BUILD[-RELEASE]"
commit_message = "bump version to {new_version}"
commit = True
tag = True
push = True
[pycalver:file_patterns]
setup.cfg =
current_version = {version}
setup.py =
"{version}",
"{pep440_version}",
README.md =
{version}
{pep440_version}
```
This probably won't cover every version number used in your project and you
will have to manually add entries to `pycalver:file_patterns`. Something
like the following may illustrate additional changes you might need to
make.
```ini
[pycalver:file_patterns]
setup.cfg =
current_version = {version}
setup.py =
version="{pep440_version}"
src/mymodule_v*/__init__.py =
__version__ = "{version}"
README.md =
[CalVer {version}]
img.shields.io/static/v1.svg?label=CalVer&message={version}&color=blue
```
To see if a pattern is found, you can use `pycalver bump --dry`, which will
leave your project files untouched and only show you a diff of the changes
it would have made.
```shell
$ pycalver bump --dry --no-fetch
INFO - Old Version: v201901.1001-beta
INFO - New Version: v201902.1002-beta
--- README.md
+++ README.md
@@ -11,7 +11,7 @@
[![Supported Python Versions][pyversions_img]][pyversions_ref]
-[![Version v201901.1001-beta][version_img]][version_ref]
+[![Version v201902.1002-beta][version_img]][version_ref]
[![PyPI Releases][pypi_img]][pypi_ref]
--- src/mymodule_v1/__init__.py
+++ src/mymodule_v1/__init__.py
@@ -1,1 +1,1 @@
-__version__ = "v201901.1001-beta"
+__version__ = "v201902.1002-beta"
--- src/mymodule_v2/__init__.py
+++ src/mymodule_v2/__init__.py
@@ -1,1 +1,1 @@
-__version__ = "v201901.1001-beta"
+__version__ = "v201902.1002-beta"
--- setup.py
+++ setup.py
@@ -44,7 +44,7 @@
name="myproject",
- version="201901.1001b0",
+ version="201902.1002b0",
license="MIT",
```
If there is no match for a pattern, bump will report an error.
```shell
$ pycalver bump --dry --no-fetch
INFO - Old Version: v201901.1001-beta
INFO - New Version: v201902.1002-beta
ERROR - No match for pattern 'img.shields.io/static/v1.svg?label=PyCalVer&message={pycalver}&color=blue'
ERROR - Pattern compiles to regex 'img\.shields\.io/static/v1\.svg\?label=PyCalVer&message=(?P<pycalver>v(?P<year>\d{4})(?P<month>(?:0[0-9]|1[0-2]))\.(?P<bid>\d{4,})(?:-(?P
<tag>(?:alpha|beta|dev|rc|post|final)))?)&color=blue'
```
The internally used regular expression is also shown, which you can use to debug the issue, for example on [regex101.com](https://regex101.com/r/ajQDTz/2).
TODO Update above link
### Legacy Patterns
> These patterns use curly braces `{}` and were the initial implementation. They are still supported and still follow their original semantics.
The `pycalver:file_patterns` section of the configuration uses a different set
of placeholders and does not use curly braces to mark placeholders. It is still
supported, but we don't recomend you use it.
Available placeholders are:
| placeholder | range / example(s) | comment |
|---------------------|---------------------|-----------------|
| `{year}` | 2019... | `%Y` |
| `{yy}` | 18, 19..99, 01, 02 | `%y` |
| `{quarter}` | 1, 2, 3, 4 | |
| `{month}` | 09, 10, 11, 12 | `%m` |
| `{iso_week}` | 00..53 | `%W` |
| `{us_week}` | 00..53 | `%U` |
| `{dom}` | 01..31 | `%d` |
| `{doy}` | 001..366 | `%j` |
| `{build}` | .1023 | lexical id |
| `{build_no}` | 1023, 20345 | ... |
| `{release}` | -alpha, -beta, -rc | --release=<tag> |
| `{release_tag}` | alpha, beta, rc | ... |
| placeholder | range / example(s) | comment |
|---------------------|---------------------|-----------------|
| `{pycalver}` | v201902.1001-beta | |
| `{pep440_pycalver}` | 201902.1b0 | |
| `{semver}` | 1.2.3 | |
### Pattern Usage
There are some limitations to keep in mind:
1. A version string cannot span multiple lines.
2. Characters generated by a placeholder cannot be escaped.
3. The timezone is always UTC.
The lack of escaping may for example be an issue with badge URLs.
You may want to put the following text in your README.md (note
that shields.io parses the two "-" dashes before `beta` as one
literal "-"):
```
https://img.shields.io/badge/myproject-v202010.1116--beta-blue.svg
```
While you could use the following pattern, which will work fine for a
while:
```ini
README.md =
/badge/myproject-{vYYYY0M.BUILD[--RELEASE]}-blue.svg
```
Eventually this will break, when you do a `final` release, at
which point the following will be put in your README.md:
```
https://img.shields.io/badge/myproject-v202010.1117--final-blue.svg
```
When what you probably wanted was this (with the `--final` tag omitted):
```
https://img.shields.io/badge/myproject-v202010.1117-blue.svg
```
### Examples
The easiest way to test a pattern is with the `pycalver test` sub-command.
```shell
$ pycalver test 'v18w01' 'vYYw0W'
New Version: v19w06
PEP440 : v19w06
# TODO (mb 2020-09-24): Update regexp pattern
$ pycalver test 'v18.01' 'vYYw0W'
ERROR - Invalid version string 'v18.01' for pattern
'vYYw0W'/'v(?P<YY>\d{2})w(?P<0W>(?:[0-4]\d|5[0-2]))'
ERROR - Invalid version 'v18.01' and/or pattern 'vYYw0W'.
```
As you can see, each pattern is internally translated to a regular expression.
All version strings in your project must match either this regular expression or
the corresponding regular expression for the PEP440 version string.
The `pycalver test` sub-command accepts the same cli flags as `pycalver
bump` to update the components that are not updated automatically (eg.
based on the calendar).
```shell
$ pycalver test 'v18.1.1' 'vYY.MINOR.PATCH'
New Version: v19.1.1
PEP440 : 19.1.1
$ pycalver test 'v18.1.1' 'vYY.MINOR.PATCH' --patch
New Version: v19.1.2
PEP440 : 19.1.2
$ pycalver test 'v18.1.2' 'vYY.MINOR.PATCH' --minor
New Version: v19.2.0
PEP440 : 19.2.0
$ pycalver test 'v201811.1051-beta' 'vYYYYMM.BUILD[-RELEASE]'
New Version: v201902.1052-beta
PEP440 : 201902.1052b0
$ pycalver test 'v201811.0051-beta' 'vYYYYMM.BUILD[-RELEASE]' --release rc
New Version: v201902.1052-rc
PEP440 : 201902.1052rc0
$ pycalver test 'v201811.0051-beta' 'vYYYYMM.BUILD[-RELEASE]' --release final
New Version: v201902.1052
PEP440 : 201902.1052
```
Note that pypi/setuptools/pip will normalize version strings to a format
defined in [PEP440][pep_440_ref]. You can use a format that deviates from
this, just be aware that version strings processed by these tools will look
different.
### Version State
The "current version" is considered global state that needs to be
stored somewhere. Typically this might be stored in a `VERSION`
file, or some other file which is part of the repository. This
creates the risk that parallel branches can have different
states. If the "current version" were defined only by files in
the local checkout, the same version might be generated for
different commits.
To avoid this issue, pycalver treats VCS tags as the canonical /
[SSOT][url_ssot] for the most recent version and attempts to
change this state in the most atomic way possible. This is why
some actions of the `pycalver` command can take a while, as it is
synchronizing with the remote repository to get the most recent
versions and to push any new version tags as soon as possible.
[url_ssot]: https://en.wikipedia.org/wiki/Single_source_of_truth
### The Current Version
The current version that will be bumped is defined either as
- Typically: The lexically largest git/mercurial tag which matches the
`version_pattern` from your config.
- Initially: Before any tags have been created (or you're not using a
supported VCS), the value of `pycalver.current_version` in `setup.cfg` /
`pyproject.toml` / `pycalver.toml`.
As part of doing `pycalver bump` and `pycalver show`, your local VCS
index is updated using `git fetch --tags`/`hg pull`.
```shell
$ time pycalver show --verbose
INFO - fetching tags from remote (to turn off use: -n / --no-fetch)
INFO - Working dir version : v202010.1018
INFO - Latest version from git tag: v202010.1019-beta
Current Version: v202010.1019-beta
PEP440 : 202010.1019b0
real 0m4,254s
$ time pycalver show --verbose --no-fetch
...
real 0m0,840s
```
Here we see that:
- The VCS had a newer version than we had locally.
- It took 4 seconds to fetch the tags from the remote repository.
This approach reduces the risk that new tags are unknown locally and makes it
less likely that the same version string is generated for different commits,
which would result in an ambiguous version tag. This can happen if multiple
maintainers produce a release at the same time or if a build system is triggered
multiple times and multiple builds run concurrently to each other.
For a small project (with only one maintainer and no build system) this is a
non-issue and you can always use `-n/--no-fetch` to skip updating the tags.
### Bump It Up
To increment the current version and publish a new version, you can use the
`pycalver bump` sub-command. `bump` is configured in the `pycalver` config
section:
```ini
[pycalver]
current_version = "v202010.1006-beta"
version_pattern = "vYYYY0M.BUILD[-RELEASE]"
commit_message = "bump version to {new_version}"
commit = True
tag = True
push = True
```
This configuration is appropriate to create a commit which
1. contains the changes to the version strings,
2. contains no other changes (unrelated to bumping the version),
3. is tagged with the new version,
4. has a version tag that is unique in the repository.
In order to make sure only changes to version strings are in the commit,
you need to make sure you have a clean VCS checkout when you invoke
`pycalver bump`.
The steps performed by `bump` are:
0. Check that your repo doesn't have any local changes.
1. *Fetch* the most recent global VCS tags from origin
(`-n`/`--no-fetch` to disable).
2. Generate a new version, incremented from the current version.
3. Update version strings in all files configured in `file_patterns`.
4. *Commit* the updated version strings.
5. *Tag* the new commit.
6. *Push* the new commit and tag.
Again, you can use `-d/--dry` to inspect the changes first.
```
$ pycalver bump --dry
--- setup.cfg
+++ setup.cfg
@@ -65,7 +65,7 @@
[pycalver]
-current_version = v202010.1005-beta
+current_version = v202010.1006-beta
version_pattern = "vYYYY0M.BUILD[-RELEASE]"
commit_message = "bump version to {new_version}"
commit = True
...
```
If everything looks OK, you can do `pycalver bump`.
```
$ pycalver bump --verbose
INFO - fetching tags from remote (to turn off use: -n / --no-fetch)
INFO - Old Version: v202010.1005-beta
INFO - New Version: v202010.1006-beta
INFO - git commit --message 'bump version to v202010.1006-beta'
INFO - git tag --annotate v202010.1006-beta --message v202010.1006-beta
INFO - git push origin v202010.1006-beta
```
### Config Parameters
TODO: Descriptions
| Config Parameter | Type | Description |
|-------------------|---------|------------------------------|
| `current_version` | string | |
| `version_pattern` | string | |
| `commit_message` | string | ¹Template fro commit message |
| `commit` | boolean | |
| `tag` | boolean | |
| `push` | boolean | |
- ¹ Available placeholders:
- `{new_version}`
- `{old_version}`
- `{new_version_pep440}`
- `{old_version_pep440}`
### CLI Reference
<!-- BEGIN pycalver --help -->
```
$ pycalver --help
Usage: pycalver [OPTIONS] COMMAND [ARGS]...
Automatically update PyCalVer version strings on python projects.
Options:
--version Show the version and exit.
--help Show this message and exit.
-v, --verbose Control log level. -vv for debug level.
Commands:
bump Increment the current version string and update project files.
grep Search file(s) for a version pattern.
init Initialize [pycalver] configuration.
show Show current version of your project.
test Increment a version number for demo purposes.
```
<!-- END pycalver --help -->
<!-- BEGIN pycalver bump --help -->
```
$ pycalver bump --help
Usage: pycalver bump [OPTIONS]
Increment the current version string and update project files.
Options:
-v, --verbose Control log level. -vv for debug level.
-f, --fetch / -n, --no-fetch Sync tags from remote origin.
-d, --dry Display diff of changes, don't rewrite files.
--release <name> Override release name of current_version.
Valid options are: alpha, beta, rc, post,
final.
--allow-dirty Commit even when working directory is has
uncomitted changes. (WARNING: The commit will
still be aborted if there are uncomitted to
files with version strings.
--major Increment major component.
-m, --minor Increment minor component.
-p, --patch Increment patch component.
-r, --release-num Increment release number.
--pin-date Leave date components unchanged.
--date <iso-date> Set explicit date in format YYYY-0M-0D (e.g.
2020-10-04).
--help Show this message and exit.
```
<!-- END pycalver bump --help -->
### Related Projects/Alternatives
The bump2version project maintains a good list of alternative and related projects: [bump2version/RELATED.md][url_bump2version_related]
[url_bump2version_related] https://github.com/c4urself/bump2version/blob/master/RELATED.md
## The PyCalVer Format
The PyCalVer format for version strings has three parts:
```
o Year and Month of Release
| o Sequential Build Number
| | o Release Tag (optional)
| | |
---+--- --+-- --+--
v202010 .1001 -beta
```
Some examples:
```
v201711.0001-alpha
v201712.0027-beta
v201801.0031
v201801.0032-post
...
v202207.18133
v202207.18134
```
This format was chosen in part to be distinctive from
others, so that users of your package can see at a glance that your project
will strive to maintain the one semantic that really matters: **newer is
better**.
To convince you of the merits of not breaking things, here are some
resources which PyCalVer was inspired by:
- ["Speculation" talk by Rich
Hicky](https://www.youtube.com/watch?v=oyLBGkS5ICk)
- [Designing a Version by Mahmoud
Hashemi](http://sedimental.org/designing_a_version.html)
- [calver.org](https://calver.org/)
- ["The cargo cult of versioning" by Kartik
Agaram](http://akkartik.name/post/versioning)
- The [bumpversion][bumpversion_ref] project, upon which
PyCalVer is partially based.
- ["Our Software Dependency Problem" by Russ Cox](https://research.swtch.com/deps)
### Parsing
These version strings can be parsed with the following regular expression:
```python
import re
# https://regex101.com/r/fnj60p/10
PYCALVER_PATTERN = r"""
\b
(?P<pycalver>
(?P<vYYYYMM>
v # "v" version prefix
(?P<year>\d{4})
(?P<month>\d{2})
)
(?P<build>
\. # "." build nr prefix
(?P<build_no>\d{4,})
)
(?P<release>
\- # "-" release prefix
(?P<release_tag>alpha|beta|dev|rc|post)
)?
)(?:\s|$)
"""
PYCALVER_REGEX = re.compile(PYCALVER_PATTERN, flags=re.VERBOSE)
version_str = "v201712.0001-alpha"
version_match = PYCALVER_REGEX.match(version_str)
assert version_match.groupdict() == {
"pycalver" : "v201712.0001-alpha",
"vYYYYMM" : "v201712",
"year" : "2017",
"month" : "12",
"build" : ".0001",
"build_no" : "0001",
"release" : "-alpha",
"release_tag": "alpha",
}
version_str = "v201712.0033"
version_match = PYCALVER_REGEX.match(version_str)
assert version_match.groupdict() == {
"pycalver" : "v201712.0033",
"vYYYYMM" : "v201712",
"year" : "2017",
"month" : "12",
"build" : ".0033",
"build_no" : "0033",
"release" : None,
"release_tag": None,
}
```
### Incrementing Behaviour
To see how version strings are incremented, we can use
`pycalver test`:
```shell
$ pycalver test v201801.1033-beta
New Version: v201902.1034-beta
PEP440 : 201902.1034b0
```
This is the simple case:
- The calendar component is updated to the current year and month.
- The build number is incremented by 1.
- The optional release tag is preserved as is.
You can explicitly update the release tag by using the `--release=<tag>` argument:
```shell
$ pycalver test v201801.1033-alpha --release=beta
New Version: v201902.1034-beta
PEP440 : 201902.1034b0
$ pycalver test v201902.1034-beta --release=final
New Version: v201902.1035
PEP440 : 201902.1035
```
To maintain lexical ordering of version numbers, the version number is padded with extra zeros using [Lexical Ids][url_pypi_lexid].
This means that the expression `older_id < newer_id` will always be true, whether you are dealing with integers or strings.
[url_pypi_lexid]: https://pypi.org/project/lexid/
## Semantics of PyCalVer
This sorting even works correctly in JavaScript!
> Disclaimer: This section can of course only be aspirational. There is nothing
> to prevent package maintainers from publishing packages with different
> semantics than what is presented here.
PyCalVer places a greater burden on package maintainers than SemVer.
Backward incompatibility is not encoded in the version string, because
**maintainers should not intentionally introduce breaking changes**. This
is great for users of a package, who can worry a bit less about an update
causing their project to break. A paranoid user can of course still pin to
a known good version, and freezing dependencies for deployments is still a
good practice, but for development, users ideally shouldn't need any
version specifiers in their requirements.txt. This way they always get the
newest bug fixes and features.
Part of the reason for the distinctive PyCalVer version string, is for
users to be able to recognize, just from looking at the version string,
that a package comes with the promise (or at least aspiration) that it
won't break, that it is safe for users to update. Compare this to a SemVer
version string, where maintainers explicitly state that an update _might_
break their program and that they _may_ have to do extra work after
updating and even if it hasn't in the past, the package maintainers
anticipate that they might make such breaking changes in the future.
In other words, the onus is on the user of a package to update their
software, if they want to update to the latest version of a package. With
PyCalVer the onus is on package maintainer to maintain backward
compatibility.
Ideally users can trust the promise of a maintainer that the following
semantics will always be true:
- Newer is compatible.
- Newer has fewer bugs.
- Newer has more features.
- Newer has equal or better performance.
Alas, the world is not ideal. So how do users and maintainers deal with changes
that violate these promises?
### Intentional Breaking Changes
> Namespaces are a honking great idea
> - let's do more of those!
>
> - The Zen of Python
If you must make a breaking change to a package, **instead of incrementing a
number**, the recommended approach with PyCalVer is to **create a whole new
namespace**. Put differently, the major version becomes part of the name of the
module or even of the package. Typically you might add a numerical suffix, eg.
`mypkg -> mypkg2`.
In the case of python distributions, you can include multiple module
packages like this.
```python
# setup.py
setuptools.setup(
name="my-package",
license="MIT",
packages=["mypkg", "mypkg2"],
package_dir={"": "src"},
...
)
```
In other words, you can ship older versions side by side with newer ones,
and users can import whichever one they need. Alternatively you can publish
a new package distribution, with new namespace, but please consider also
renaming the module.
```python
# setup.py
setuptools.setup(
name="my-package-v2",
license="MIT",
packages=["mypkg2"],
package_dir={"": "src"},
...
)
```
Users will have an easier time working with your package if `import mypkg2`
is enough to determine which version of your project they are using. A further
benefit of creating multiple modules is that users can import both old and
new modules in the same environment and can use some packages which depend
on the old version as well as some that depend on the new version. The
downside for users, is that they may have to do minimal changes to their
code, even if the breaking change did not affect them.
```diff
- import mypkg
+ import mypkg2
def usage_code():
- mypkg.myfun()
+ mypkg2.myfun()
```
### Costs and Benefits
If this seems like overkill because it's a lot of work for you as a
maintainer, consider first investing some time in your tools, so you
minimize future work required to create new packages. I've [done this for
my personal projects][bootstrapit_ref], but you may find [other
approaches][cookiecutter_ref] to be more appropriate for your use.
If this seems like overkill because you're not convinced that imposing a
very small burden on users is such a big deal, consider that your own
projects may indirectly depend on dozens of libraries which you've never
even heard of. If every maintainer introduced breaking changes only once
per year, users who depend on only a dozen libraries would be dealing with
packaging issues every month! In other words: *Breaking things is a big
deal*. A bit of extra effort for a few maintainers seems like a fair trade
to lower the effort imposed on many users, who would be perfectly happy to
continue using the old code until _they_ decide when to upgrade.
### Unintentional Breaking Changes
The other kind of breaking change is the non-intentional kind, otherwise
known as a "bug" or "regression". Realize first of all, that it is
impossible for any versioning system to encode that this has happened:
Since the maintainer isn't knowingly introducing a bug they naturally can't
update their version numbers to reflect what they don't know about. Instead
we have to deal with these issues after the fact.
The first thing a package maintainer can do is to minimize the chance of
inflicting buggy software on users. After any non-trivial (potentially breaking)
change, it is a good practice to first create an `-alpha`/`-beta`/`-rc` release.
These so called `--pre` releases are intended to be downloaded only by the few
and the brave: Those who are willing to participate in testing. After any issues
are ironed out with the `--pre` releases, a `final` release can be made for the
wider public.
Note that the default behaviour of `pip install <package>` (without any version
specifier) is to download the latest `final` release. It will download a `--pre`
release *only* if
1. no `final` release is available
2. the `--pre` flag is explicitly used, or
3. if the requirement specifier _explicitly_ includes the version number of a
pre release, eg. `pip install mypkg==v202009.1007-alpha`.
Should a release include a bug (heaven forbid and despite all precautions),
then the maintainer should publish a new release which either fixes the bug
or reverts the change. If users previously downloaded a version of the
package which included the bug, they only have to do `pip install --upgrade
<package>` and the issue will be resolved.
Perhaps a timeline will illustrate more clearly:
```
v202008.1665 # last stable release
v202008.1666-beta # pre release for testers
v201901.1667 # final release after testing
# bug is discovered which effects v202008.1666-beta and v201901.1667
v201901.1668-beta # fix is issued for testers
v201901.1669 # fix is issued everybody
# Alternatively, revert before fixing
v201901.1668 # same as v202008.1665
v201901.1669-beta # reintroduce change from v202008.1666-beta + fix
v201901.1670 # final release after testing
```
In the absolute worst case, a change is discovered to break backward
compatibility, but the change is nonetheless considered to be desirable. At that
point, a new release should be made to revert the change.
This allows 1. users who _were_ exposed to the breaking change to update to the
latest release and get the old (working) code again, and 2. users who _were not_
exposed to the breaking change to never even know anything was broken.
Remember that the goal is to always make things easy for users who have
your package as a dependency. If there is any issue whatsoever, all they
should have to do is `pip install --update`. If this doesn't work, they may
have to *temporarily* pin to a known good version, until a fixed release
has been published.
After this immediate fire has been extinguished, if the breaking change is
worth keeping, then **create a new module or even a new package**. This
package will perhaps have 99% overlap to the previous one and the old one
may eventually be abandoned.
```
mypkg v202008.1665 # last stable release
mypkg v202008.1666-rc # pre release for testers
mypkg v201901.1667 # final release after testing period
# bug is discovered in v202008.1666-beta and v201901.1667
mypkg v201901.1668 # same as v202008.1665
# new package is created with compatibility breaking code
mypkg2 v201901.1669 # same as v201901.1667
mypkg v201901.1669 # updated readme, declaring support
# level for mypkg, pointing to mypgk2
# and documenting how to upgrade.
```
### Pinning is not a Panacea
Freezing your dependencies by using `pip freeze` to create a file with packages
pinned to specific version numbers is great to get a stable and repeatable
deployment.
The main problem with pinning is that it is another burden imposed on users,
and it is a burden which in practice only some can bear. The vast majority of
users either 1) pin their dependencies and update them without determining what
changed or if it is safe for them to update, or 2) pin their dependencies and
forget about them. In case 1 the only benefit is that users might at least be
aware of when an update happened, so they can perhaps correlate that a new bug
in their software might be related to a recent update. Other than that, keeping
tabs on dependencies and updating without diligence is hardly better than not
having pinned at all. In case 2, an insurmountable debt will pile up and the
dependencies of a project are essentially frozen in the past.
Yes, it is true that users will be better off if they have sufficient test
coverage to determine for themselves that their code is not broken even after
their dependencies are updated. It is also true however, that a package
maintainer is usually in a better position to judge if a change might cause
something to break.
### Zeno's 1.0 and The Eternal Beta
There are two opposite approaches to backward compatibility which find a
reflection in the version numbers they use. In the case of SemVer, if a
project has a commitment to backward compatibility, it may end up never
incriminating the major version, leading to the [Zeno 1.0
paradox][zeno_1_dot_0_ref]. On the other end are projects that avoid any
commitment to backward compatibility and forever keep the "beta" label.
Of course an unpaid Open Source developer *does not owe anybody a
commitment to backward compatibility*. Especially when a project is young
and going through major changes, such a commitment may not make any sense.
For these cases you can still use PyCalVer, just so long as there is a big
fat warning at the top of your README, that your project is not ready for
production yet.
Note that there is a difference between software that is considered to be
in a "beta" state and individual releases which have a `-beta` tag. These
do not mean the same thing. In the case of releases of python packages, the
release tag (`-alpha`, `-beta`, `-rc`) says something about the stability
of a *particular release*. This is similar ([perhaps
identical][pep_101_ref]) to the meaning of release tags used by the CPython
interpreter. A release tag is not a statement about the general stability
of the software as a whole, it is metadata about a particular release
artifact of a package, eg. a `.whl` file.
[setuptools_ref]: https://setuptools.readthedocs.io/en/latest/setuptools.html#specifying-your-project-s-version
[pep_440_ref]: https://www.python.org/dev/peps/pep-0440/
[pep_440_normalzation_ref]: https://www.python.org/dev/peps/pep-0440/#id31
[zeno_1_dot_0_ref]: http://sedimental.org/designing_a_version.html#semver-and-release-blockage
[pep_101_ref]: https://www.python.org/dev/peps/pep-0101/
[bumpversion_ref]: https://github.com/peritus/bumpversion
[bootstrapit_ref]: https://gitlab.com/mbarkhau/bootstrapit
[cookiecutter_ref]: https://cookiecutter.readthedocs.io
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