Created new visitor system called "internal traversal" that
applies a data driven approach to the concept of a class that
defines its own traversal steps, in contrast to the existing
style of traversal now known as "external traversal" where
the visitor class defines the traversal, i.e. the SQLCompiler.
The internal traversal system now implements get_children(),
_copy_internals(), compare() and _cache_key() for most Core elements.
Core elements with special needs like Select still implement
some of these methods directly however most of these methods
are no longer explicitly implemented.
The data-driven system is also applied to ORM elements that
take part in SQL expressions so that these objects, like mappers,
aliasedclass, query options, etc. can all participate in the
cache key process.
Still not considered is that this approach to defining traversibility
will be used to create some kind of generic introspection system
that works across Core / ORM. It's also not clear if
real statement caching using the _cache_key() method is feasible,
if it is shown that running _cache_key() is nearly as expensive as
compiling in any case. Because it is data driven, it is more
straightforward to optimize using inlined code, as is the case now,
as well as potentially using C code to speed it up.
In addition, the caching sytem now accommodates for anonymous
name labels, which is essential so that constructs which have
anonymous labels can be cacheable, that is, their position
within a statement in relation to other anonymous names causes
them to generate an integer counter relative to that construct
which will be the same every time. Gathering of bound parameters
from any cache key generation is also now required as there is
no use case for a cache key that does not extract bound parameter
values.
Applies-to: #4639
Change-Id: I0660584def8627cad566719ee98d3be045db4b8d
Reworked the :meth:`.ClauseElement.compare` methods in terms of a new
visitor-based approach, and additionally added test coverage ensuring that
all :class:`.ClauseElement` subclasses can be accurately compared
against each other in terms of structure. Structural comparison
capability is used to a small degree within the ORM currently, however
it also may form the basis for new caching features.
Fixes: #4336
Change-Id: I581b667d8e1642a6c27165cc9f4aded1c66effc6
Applied on top of a pure run of black -l 79 in
I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9, this set of changes
resolves all remaining flake8 conditions for those codes
we have enabled in setup.cfg.
Included are resolutions for all remaining flake8 issues
including shadowed builtins, long lines, import order, unused
imports, duplicate imports, and docstring issues.
Change-Id: I4f72d3ba1380dd601610ff80b8fb06a2aff8b0fe
This is a straight reformat run using black as is, with no edits
applied at all.
The black run will format code consistently, however in
some cases that are prevalent in SQLAlchemy code it produces
too-long lines. The too-long lines will be resolved in the
following commit that will resolve all remaining flake8 issues
including shadowed builtins, long lines, import order, unused
imports, duplicate imports, and docstring issues.
Change-Id: I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9
No SQLA built-in subclasses ColumnElement without specifying
an alternate visit_name, and user defined ColumnElement
subclasses should avoid being treated like ColumnClause,
e.g. where a Table is present.
Fixes: #4142
Change-Id: I15ed09ba8bdebae4cb0c7e5e5df3f59351477577
Fixes the comparison of bindparam() objects based on
the "callable" parameter being present which helps to correctly
detect use_get, and also checks for "callable" when detecting
parameters for value substitution and will not impact the
object if present.
Change-Id: I4c93ee5d404d2648dd9835beeae0c5fb67e37d19
Fixes: #3767
Fixed bug where the "simple many-to-one" condition that allows lazy
loading to use get() from identity map would fail to be invoked if the
primaryjoin of the relationship had multiple clauses separated by AND
which were not in the same order as that of the primary key columns
being compared in each clause. This ordering
difference occurs for a composite foreign key where the table-bound
columns on the referencing side were not in the same order in the .c
collection as the primary key columns on the referenced side....which
in turn occurs a lot if one is using declarative mixins and/or
declared_attr to set up columns.
Change-Id: I66cce74f614c04ed693dc0d58ac8c952b2f8ae54
Fixes: #3788
Mike Bayer