title: sqlalchemy.engine default Example Code
category: page
slug: sqlalchemy-engine-default-examples
sortorder: 500031024
toc: False
sidebartitle: sqlalchemy.engine default
meta: Python example code that shows how to use the default callable from the sqlalchemy.engine module of the SQLAlchemy project.


`default` is a callable within the `sqlalchemy.engine` module of the SQLAlchemy project.

<a href="/sqlalchemy-engine-connection-examples.html">Connection</a>,
<a href="/sqlalchemy-engine-engine-examples.html">Engine</a>,
<a href="/sqlalchemy-engine-create-engine-examples.html">create_engine</a>,
and <a href="/sqlalchemy-engine-url-examples.html">url</a>
are several other callables with code examples from the same `sqlalchemy.engine` package.

## Example 1 from alembic
[Alembic](https://github.com/sqlalchemy/alembic)
([project documentation](https://alembic.sqlalchemy.org/) and
[PyPI page](https://pypi.org/project/alembic/))
is a data migrations tool used with [SQLAlchemy](/sqlalchemy.html) to make
database schema changes. The Alembic project is open sourced under the
[MIT license](https://github.com/sqlalchemy/alembic/blob/master/LICENSE).

[**alembic / alembic / testing / assertions.py**](https://github.com/sqlalchemy/alembic/blob/master/alembic/testing/assertions.py)

```python
# assertions.py
from __future__ import absolute_import

import re

from sqlalchemy import util
~~from sqlalchemy.engine import default
from sqlalchemy.testing.assertions import _expect_warnings
from sqlalchemy.testing.assertions import eq_  # noqa
from sqlalchemy.testing.assertions import is_  # noqa
from sqlalchemy.testing.assertions import is_false  # noqa
from sqlalchemy.testing.assertions import is_not_  # noqa
from sqlalchemy.testing.assertions import is_true  # noqa
from sqlalchemy.testing.assertions import ne_  # noqa
from sqlalchemy.util import decorator

from ..util.compat import py3k


def assert_raises(except_cls, callable_, *args, **kw):
    try:
        callable_(*args, **kw)
        success = False
    except except_cls:
        success = True

    assert success, "Callable did not raise an exception"


def assert_raises_message(except_cls, msg, callable_, *args, **kwargs):
    try:


## ... source file abbreviated to get to default examples ...


            e,
        )
        print(util.text_type(e).encode("utf-8"))


def eq_ignore_whitespace(a, b, msg=None):

    a = re.sub(r"^\s+?|\n", "", a)
    a = re.sub(r" {2,}", " ", a)
    b = re.sub(r"^\s+?|\n", "", b)
    b = re.sub(r" {2,}", " ", b)

    if py3k:
        b = re.sub(r"!U", "", b)
    else:
        b = re.sub(r"!U", "u", b)

    assert a == b, msg or "%r != %r" % (a, b)


_dialect_mods = {}


def _get_dialect(name):
    if name is None or name == "default":
~~        return default.DefaultDialect()
    else:
        try:
            dialect_mod = _dialect_mods[name]
        except KeyError:
            dialect_mod = getattr(
                __import__("sqlalchemy.dialects.%s" % name).dialects, name
            )
            _dialect_mods[name] = dialect_mod
        d = dialect_mod.dialect()
        if name == "postgresql":
            d.implicit_returning = True
        elif name == "mssql":
            d.legacy_schema_aliasing = False
        return d


def expect_warnings(*messages, **kw):
    return _expect_warnings(Warning, messages, **kw)


def emits_python_deprecation_warning(*messages):

    @decorator
    def decorate(fn, *args, **kw):


## ... source file continues with no further default examples...

```

