diff options
Diffstat (limited to 'lib/sqlalchemy/engine/strategies.py')
| -rw-r--r-- | lib/sqlalchemy/engine/strategies.py | 54 |
1 files changed, 38 insertions, 16 deletions
diff --git a/lib/sqlalchemy/engine/strategies.py b/lib/sqlalchemy/engine/strategies.py index 168a9c4ab..a0a6445fd 100644 --- a/lib/sqlalchemy/engine/strategies.py +++ b/lib/sqlalchemy/engine/strategies.py @@ -1,4 +1,4 @@ -"""Define different strategies for creating new instances of sql.Engine. +"""Strategies for creating new instances of Engine types. By default there are two, one which is the "thread-local" strategy, one which is the "plain" strategy. @@ -15,9 +15,10 @@ from sqlalchemy import pool as poollib strategies = {} class EngineStrategy(object): - """Define a function that receives input arguments and produces an - instance of sql.Engine, typically an instance - sqlalchemy.engine.base.Engine or a subclass. + """An adaptor that processes input arguements and produces an Engine. + + Provides a ``create`` method that receives input arguments and + produces an instance of base.Engine or a subclass. """ def __init__(self, name): @@ -30,11 +31,13 @@ class EngineStrategy(object): strategies[self.name] = self def create(self, *args, **kwargs): - """Given arguments, returns a new sql.Engine instance.""" + """Given arguments, returns a new Engine instance.""" raise NotImplementedError() class DefaultEngineStrategy(EngineStrategy): + """Base class for built-in stratgies.""" + def create(self, name_or_url, **kwargs): # create url.URL object u = url.make_url(name_or_url) @@ -54,9 +57,9 @@ class DefaultEngineStrategy(EngineStrategy): if k in kwargs: dbapi_args[k] = kwargs.pop(k) dbapi = dialect_cls.dbapi(**dbapi_args) - + dialect_args['dbapi'] = dbapi - + # create dialect dialect = dialect_cls(**dialect_args) @@ -78,9 +81,13 @@ class DefaultEngineStrategy(EngineStrategy): getattr(dialect_cls, 'poolclass', poollib.QueuePool)) pool_args = {} - # consume pool arguments from kwargs, translating a few of the arguments + # consume pool arguments from kwargs, translating a few of + # the arguments + translate = {'echo': 'echo_pool', + 'timeout': 'pool_timeout', + 'recycle': 'pool_recycle'} for k in util.get_cls_kwargs(poolclass): - tk = {'echo':'echo_pool', 'timeout':'pool_timeout', 'recycle':'pool_recycle'}.get(k, k) + tk = translate.get(k, k) if tk in kwargs: pool_args[k] = kwargs.pop(tk) pool_args['use_threadlocal'] = self.pool_threadlocal() @@ -100,8 +107,14 @@ class DefaultEngineStrategy(EngineStrategy): # all kwargs should be consumed if kwargs: - raise TypeError("Invalid argument(s) %s sent to create_engine(), using configuration %s/%s/%s. Please check that the keyword arguments are appropriate for this combination of components." % (','.join(["'%s'" % k for k in kwargs]), dialect.__class__.__name__, pool.__class__.__name__, engineclass.__name__)) - + raise TypeError( + "Invalid argument(s) %s sent to create_engine(), " + "using configuration %s/%s/%s. Please check that the " + "keyword arguments are appropriate for this combination " + "of components." % (','.join(["'%s'" % k for k in kwargs]), + dialect.__class__.__name__, + pool.__class__.__name__, + engineclass.__name__)) return engineclass(pool, dialect, u, **engine_args) def pool_threadlocal(self): @@ -111,6 +124,8 @@ class DefaultEngineStrategy(EngineStrategy): raise NotImplementedError() class PlainEngineStrategy(DefaultEngineStrategy): + """Strategy for configuring a regular Engine.""" + def __init__(self): DefaultEngineStrategy.__init__(self, 'plain') @@ -123,6 +138,8 @@ class PlainEngineStrategy(DefaultEngineStrategy): PlainEngineStrategy() class ThreadLocalEngineStrategy(DefaultEngineStrategy): + """Strategy for configuring an Engine with thredlocal behavior.""" + def __init__(self): DefaultEngineStrategy.__init__(self, 'threadlocal') @@ -136,11 +153,15 @@ ThreadLocalEngineStrategy() class MockEngineStrategy(EngineStrategy): - """Produces a single Connection object which dispatches statement executions - to a passed-in function""" + """Strategy for configuring an Engine-like object with mocked execution. + + Produces a single mock Connectable object which dispatches + statement execution to a passed-in function. + """ + def __init__(self): EngineStrategy.__init__(self, 'mock') - + def create(self, name_or_url, executor, **kwargs): # create url.URL object u = url.make_url(name_or_url) @@ -165,12 +186,13 @@ class MockEngineStrategy(EngineStrategy): engine = property(lambda s: s) dialect = property(lambda s:s._dialect) - + def contextual_connect(self, **kwargs): return self def compiler(self, statement, parameters, **kwargs): - return self._dialect.compiler(statement, parameters, engine=self, **kwargs) + return self._dialect.compiler( + statement, parameters, engine=self, **kwargs) def create(self, entity, **kwargs): kwargs['checkfirst'] = False |