Add ability for `__post_init__` method to be defined. #111

tbeadle · 2016-11-11T04:20:11Z

If this method is defined for a class, it will get executed at the end
of __init__. Previously, there was no way to extend what was
done during __init__ when using @attr.s.

src/attr/_make.py

@@ -680,6 +680,10 @@ def fmt_setter_with_converter(attr_name, value_var):
                                                    a.name))
        names_for_globals[val_name] = a.validator
        names_for_globals[attr_name] = a
+    lines.extend([
+        "func = getattr(self, '__post_init__', None)",


codecov-io · 2016-11-11T12:29:47Z

Current coverage is 100% (diff: 100%)

Merging #111 into master will not change coverage

@@           master   #111   diff @@
====================================
  Files           8      8          
  Lines         466    468     +2   
  Methods         0      0          
  Messages        0      0          
  Branches      105    106     +1   
====================================
+ Hits          466    468     +2   
  Misses          0      0          
  Partials        0      0

Powered by Codecov. Last update cbfb229...7724d31

src/attr/_make.py

+    script, globs = _attrs_to_script(
+        attrs,
+        frozen,
+        post_init=hasattr(cls, '__post_init__')


hynek

I have added a bunch of comments many of which arguably should have been covered by the contribution guide so I’ve added it to my own todo list to fix that.

If you have problems with Hypothesis, offering candy to @Tinche always helped for me. ;)

Thank you for your contribution! And please remember to ping the ticket once you’re done.

src/attr/_make.py

@@ -540,7 +544,7 @@ def validate(inst):
            a.validator(inst, a, getattr(inst, a.name))


-def _attrs_to_script(attrs, frozen):
+def _attrs_to_script(attrs, frozen, post_init=False):


src/attr/_make.py

@@ -680,6 +684,8 @@ def fmt_setter_with_converter(attr_name, value_var):
                                                    a.name))
        names_for_globals[val_name] = a.validator
        names_for_globals[attr_name] = a
+    if post_init:
+        lines.append("self.__post_init__()")


tests/test_make.py

@@ -302,6 +302,22 @@ class D(object):
        assert C.D.__name__ == "D"
        assert C.D.__qualname__ == C.__qualname__ + ".D"

+    def test_post_init(self):


docs/examples.rst

@@ -551,6 +551,25 @@ You can still have power over the attributes if you pass a dictionary of name: `
   >>> i.y
   []

+Sometimes, you want to have your class's ``__init__`` method do more than just


CHANGELOG.rst

@@ -13,6 +13,9 @@ Changes:

 - Don't overwrite ``__name__`` with ``__qualname__`` for ``attr.s(slots=True)`` classes.
  `#99 <https://github.com/hynek/attrs/issues/99>`_
+- Allow for a ``__post_init__`` method that, if defined, will get executed at


tests/test_make.py

+                self2.z = self2.x + self2.y
+
+        c = C(x=10, y=20)
+        assert hasattr(c, 'z')


tests/test_make.py

+
+        c = C(x=10, y=20)
+        assert hasattr(c, 'z')
+        assert c.z == 30


If this method is defined for a class, it will get executed at the end of ``__init__``. Previously, there was no way to extend what was done during ``__init__`` when using ``@attr.s``.

wearpants · 2016-11-15T11:43:33Z

Late to the party, but yes absolutely post conversion

hynek · 2016-11-20T13:49:28Z

I’ve fixed it up so we don’t have ping-pong over minutiae anymore, thank you very much for your contribution!

I’ve decided to rename __post_init__ to __attrs_post_init__ for consistency with __attrs_attrs__ and to be explicit about it’s heritage.

If someone has good arguments against it, feel free to open a new issue before 16.3.0 is out.

hynek reviewed Nov 11, 2016

View reviewed changes

src/attr/_make.py

@@ -680,6 +680,10 @@ def fmt_setter_with_converter(attr_name, value_var):

a.name))

names_for_globals[val_name] = a.validator

names_for_globals[attr_name] = a

lines.extend([

"func = getattr(self, '__post_init__', None)",

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tbeadle force-pushed the post_init branch from 6106e0d to 1ac1cdd Compare November 11, 2016 12:29

hynek reviewed Nov 11, 2016

View reviewed changes

src/attr/_make.py

script, globs = _attrs_to_script(

attrs,

frozen,

post_init=hasattr(cls, '__post_init__')

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tbeadle force-pushed the post_init branch from 1ac1cdd to 0f6636b Compare November 11, 2016 13:14

hynek requested changes Nov 13, 2016

View reviewed changes

Add ability for __post_init__ method to be defined.

7724d31

If this method is defined for a class, it will get executed at the end of ``__init__``. Previously, there was no way to extend what was done during ``__init__`` when using ``@attr.s``.

tbeadle force-pushed the post_init branch from 0f6636b to 7724d31 Compare November 14, 2016 15:03

hynek added this to the 16.3.0 milestone Nov 19, 2016

hynek closed this in 1fbaa20 Nov 20, 2016

hynek mentioned this pull request Nov 20, 2016

init hooks #68

Closed

wsanchez mentioned this pull request Feb 17, 2017

frozen class is made immutable before __attrs_post_init__ gets a turn #147

Closed

Add ability for `__post_init__` method to be defined. #111

Add ability for `__post_init__` method to be defined. #111

tbeadle commented Nov 11, 2016

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codecov-io commented Nov 11, 2016 •

edited

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wearpants commented Nov 15, 2016

hynek commented Nov 20, 2016

Add ability for __post_init__ method to be defined. #111

Add ability for __post_init__ method to be defined. #111

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tbeadle commented Nov 11, 2016

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codecov-io commented Nov 11, 2016 • edited

Current coverage is 100% (diff: 100%)

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wearpants commented Nov 15, 2016

hynek commented Nov 20, 2016

Add ability for `__post_init__` method to be defined. #111

Add ability for `__post_init__` method to be defined. #111

codecov-io commented Nov 11, 2016 •

edited