improve LazyImport

[videlec]

The LazyImport objects suffer several problems

1. copy and deepcopy are broken

sage: from sage.misc.lazy_import import LazyImport
sage: sage.all.foo = [1, 2]
sage: lazy_foo = LazyImport('sage.all', 'foo')
sage: a = copy(lazy_foo)
sage: a
[1, 2]
sage: a[0] = 18
sage: lazy_foo
[18, 2]

2. Most doctests use lazy_import rather than LazyImport. The former modifies the namespace so that the name actually points to the object afterwards. Compare

sage: lazy_import('sage.rings.all', 'ZZ', 'lazy_ZZ')
sage: type(lazy_ZZ)
<class 'sage.misc.lazy_import.LazyImport'>
sage: _ = lazy_ZZ(3)
sage: type(lazy_ZZ)
<class 'sage.rings.integer_ring.IntegerRing_class'>

with

sage: from sage.misc.lazy_import import LazyImport
sage: lazy_ZZ = LazyImport('sage.rings.all', 'ZZ')
sage: _ = lazy_ZZ(3)
sage: type(lazy_ZZ)
<class 'sage.misc.lazy_import.LazyImport'>

In the former version, any code that uses more than once the lazy object actually uses it only once.

3. It is not checked that lazy imported module resolves correctly... and it is not the case

sage: LinearCodeFromVectorSpace._get_object()
Traceback (most recent call last):
...
AttributeError: module 'sage.coding.linear_code' has no attribute 'LinearCodeFromVectorSpace'

Follow-up: #31656

Depends on #31648

CC: @kliem

Component: misc

Author: Vincent Delecroix

Branch/Commit: 99ad007

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/31650

[videlec]

Description changed:

--- 
+++ 
@@ -37,3 +37,12 @@
     In the former version, any code that uses more than once the lazy object actually uses it only once.
 
 3. Calling `__module__` triggers `get_object` whereas we could return what is contained in the `_module` attribute. This would solve #31643 but it is likely to be a bad idea as the module from which an object is imported is not necessarily the module in which it is defined.
+
+4. It is not checked that lazy imported module resolves correctly... and it is not the case
+
+```
+sage: LinearCodeFromVectorSpace._get_object()                                                                                                                                                  
+Traceback (most recent call last):
+...
+AttributeError: module 'sage.coding.linear_code' has no attribute 'LinearCodeFromVectorSpace'
+```

[videlec]

Author: Vincent Delecroix

[videlec]

Description changed:

--- 
+++ 
@@ -10,7 +10,7 @@
 sage: a
 [1, 2]
 sage: a[0] = 18
-sage: a
+sage: lazy_foo
 [18, 2]
 ```
 
@@ -36,12 +36,12 @@
 ```
     In the former version, any code that uses more than once the lazy object actually uses it only once.
 
-3. Calling `__module__` triggers `get_object` whereas we could return what is contained in the `_module` attribute. This would solve #31643 but it is likely to be a bad idea as the module from which an object is imported is not necessarily the module in which it is defined.
+3. Calling `__module__` triggers `get_object` whereas we could return what is contained in the `_module` attribute. This would solve #31643.
 
 4. It is not checked that lazy imported module resolves correctly... and it is not the case
 
 ```
-sage: LinearCodeFromVectorSpace._get_object()                                                                                                                                                  
+sage: LinearCodeFromVectorSpace._get_object()
 Traceback (most recent call last):
 ...
 AttributeError: module 'sage.coding.linear_code' has no attribute 'LinearCodeFromVectorSpace'

[videlec]

Commit: 879debd

[videlec]

New commits:

f9b8599	31648: disable jedi by default
fe2b431	typo
dad63d0	31650: improvements to lazy_import
324419b	31650: resolve all lazy imports in a doctest
879debd	31650: also make all lazy imports also work in the console

[videlec]

Description changed:

--- 
+++ 
@@ -36,9 +36,7 @@
 ```
     In the former version, any code that uses more than once the lazy object actually uses it only once.
 
-3. Calling `__module__` triggers `get_object` whereas we could return what is contained in the `_module` attribute. This would solve #31643.
-
-4. It is not checked that lazy imported module resolves correctly... and it is not the case
+3. It is not checked that lazy imported module resolves correctly... and it is not the case
 
 ```
 sage: LinearCodeFromVectorSpace._get_object()
@@ -46,3 +44,5 @@
 ...
 AttributeError: module 'sage.coding.linear_code' has no attribute 'LinearCodeFromVectorSpace'
 ```
+
+Follow-up: #31656

[videlec]

Branch: u/vdelecroix/31650

[videlec]

Dependencies: #31648

[videlec]

Description changed:

--- 
+++ 
@@ -30,7 +30,6 @@
 sage: from sage.misc.lazy_import import LazyImport
 sage: lazy_ZZ = LazyImport('sage.rings.all', 'ZZ')
 sage: _ = lazy_ZZ(3)
-3
 sage: type(lazy_ZZ)
 <class 'sage.misc.lazy_import.LazyImport'>
 ```