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
The doc edits in e45878bf4f9cdfb714dce8b2a4d705178947674d triggered a doctest and a pep8 failure. Change-Id: I41c6cba9bab2d3721d9c6280be47eec32f4b4736
sphinx is not generating the docs for func. cross-copy __doc__ and also add more links. Fixes: #4922 Change-Id: I5512111d726b6fcf9821be730c9e29adc73c95cb
The :func:`.select` construct and related constructs now allow for duplication of column labels and columns themselves in the columns clause, mirroring exactly how column expressions were passed in. This allows the tuples returned by an executed result to match what was SELECTed for in the first place, which is how the ORM :class:`.Query` works, so this establishes better cross-compatibility between the two constructs. Additionally, it allows column-positioning-sensitive structures such as UNIONs (i.e. :class:`.CompoundSelect`) to be more intuitively constructed in those cases where a particular column might appear in more than one place. To support this change, the :class:`.ColumnCollection` has been revised to support duplicate columns as well as to allow integer index access. Fixes: #4753 Change-Id: Ie09a8116f05c367995c1e43623c51e07971d3bf0
This is a very useful assertion which prevents unused variables from being set up allows code to be more readable and sometimes even more efficient. test suites seem to be where the most problems are and there do not seem to be documentation examples that are using this, or at least the linter is not taking effect within rst blocks. Change-Id: I2b3341d8dd14da34879d8425838e66a4b9f8e27d
A major refactoring of all the functions handle all detection of Core argument types as well as perform coercions into a new class hierarchy based on "roles", each of which identify a syntactical location within a SQL statement. In contrast to the ClauseElement hierarchy that identifies "what" each object is syntactically, the SQLRole hierarchy identifies the "where does it go" of each object syntactically. From this we define a consistent type checking and coercion system that establishes well defined behviors. This is a breakout of the patch that is reorganizing select() constructs to no longer be in the FromClause hierarchy. Also includes a rename of as_scalar() into scalar_subquery(); deprecates automatic coercion to scalar_subquery(). Partially-fixes: #4617 Change-Id: I26f1e78898693c6b99ef7ea2f4e7dfd0e8e1a1bd
Fixed that the :class:`.GenericFunction` class was inadvertently registering itself as one of the named functions. Pull request courtesy Adrien Berchet. Fixes: #4653 Closes: #4654 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/4654 Pull-request-sha: 1112b89f0d5af8cd5ba88cef744698a79dbdb963 Change-Id: Ia0d366d3bff44a763aa496287814278dff732a19
Registered function names based on :class:`.GenericFunction` are now retrieved in a case-insensitive fashion in all cases, removing the deprecation logic from 1.3 which temporarily allowed multiple :class:`.GenericFunction` objects to exist with differing cases. A :class:`.GenericFunction` that replaces another on the same name whether or not it's case sensitive emits a warning before replacing the object. Fixes: #4649 Change-Id: I265ae19833132db07ed5b5ae40c4d24f659b1ab3
The :class:`.GenericFunction` namespace is being migrated so that function names are looked up in a case-insensitive manner, as SQL functions do not collide on case sensitive differences nor is this something which would occur with user-defined functions or stored procedures. Lookups for functions declared with :class:`.GenericFunction` now use a case insensitive scheme, however a deprecation case is supported which allows two or more :class:`.GenericFunction` objects with the same name of different cases to exist, which will cause case sensitive lookups to occur for that particular name, while emitting a warning at function registration time. Thanks to Adrien Berchet for a lot of work on this complicated feature. Fixes: #4569 Closes: #4570 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/4570 Pull-request-sha: 37d4f3322b6bace88c99b959cb1916dbbc57610e Change-Id: Ief07c6eb55bf398f6aad85b60ef13ee6d1173109
This leverages the work started in #4336 to allow ClauseElement structures to be cachable based on structure, not just identity. Change-Id: Ia99ddeb5353496dd7d61243245685f02b98d8100