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Diffstat (limited to 'docs/build/api')
| -rw-r--r-- | docs/build/api/overview.rst | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/docs/build/api/overview.rst b/docs/build/api/overview.rst index 048d1e6..3e6bec8 100644 --- a/docs/build/api/overview.rst +++ b/docs/build/api/overview.rst @@ -14,12 +14,21 @@ This module produces a :class:`.Config` object and passes it to the appropriate function in :ref:`alembic.command.toplevel`. Functions within :ref:`alembic.command.toplevel` will typically instantiate an :class:`.ScriptDirectory` instance, which represents the collection of -version files, and an :class:`.EnvironmentContext`, which represents a -configurational object passed to the environment's ``env.py`` script. +version files, and an :class:`.EnvironmentContext`, which is a configurational +facade passed to the environment's ``env.py`` script. -Within the execution of ``env.py``, a :class:`.MigrationContext` -object is produced when the :meth:`.EnvironmentContext.configure` -method is called. :class:`.MigrationContext` is the gateway to the database +The :class:`.EnvironmentContext` object is the primary object used within +the ``env.py`` script, whose main purpose is that of a facade for creating and using +a :class:`.MigrationContext` object, which is the actual migration engine +that refers to a database implementation. The primary method called +on this object within an ``env.py`` script is the +:meth:`.EnvironmentContext.configure` method, which sets up the +:class:`.MigrationContext` with database connectivity and behavioral +configuration. It also supplies methods for transaction demarcation and +migration running, but these methods ultimately call upon the +:class:`.MigrationContext` that's been configured. + +:class:`.MigrationContext` is the gateway to the database for other parts of the application, and produces a :class:`.DefaultImpl` object which does the actual database communication, and knows how to create the specific SQL text of the various DDL directives such as |