Commit bc4b3339 authored by Tim Peters's avatar Tim Peters

English repairs.

parent e517732c
...@@ -39,13 +39,13 @@ and abort changes: ...@@ -39,13 +39,13 @@ and abort changes:
>>> root['name'] >>> root['name']
'bob' 'bob'
Now, lets look at an application that manages funds for people. Now, let's look at an application that manages funds for people.
It allows deposits and debits to be entered for multiple people. It allows deposits and debits to be entered for multiple people.
It accepts a sequence of entries and generates a sequence of status It accepts a sequence of entries and generates a sequence of status
messages. For each entry, it applies the change and then validates messages. For each entry, it applies the change and then validates
the user's account. If the user's account is invalid, we role back the user's account. If the user's account is invalid, we roll back
the change for that entry. The success or failure of an entry is the change for that entry. The success or failure of an entry is
indicated in the output status. First we'll initialize some accounts: indicated in the output status. First we'll initialize some accounts:
>>> root['bob-balance'] = 0.0 >>> root['bob-balance'] = 0.0
>>> root['bob-credit'] = 0.0 >>> root['bob-credit'] = 0.0
...@@ -60,8 +60,7 @@ Now, we'll define a validation function to validate an account: ...@@ -60,8 +60,7 @@ Now, we'll define a validation function to validate an account:
... raise ValueError('Overdrawn', name) ... raise ValueError('Overdrawn', name)
And a function to apply entries. If the function fails in some And a function to apply entries. If the function fails in some
unexpected way, it rolls back all of it's changes and unexpected way, it rolls back all of its changes and prints the error:
prints the error:
>>> def apply_entries(entries): >>> def apply_entries(entries):
... savepoint = transaction.savepoint() ... savepoint = transaction.savepoint()
...@@ -103,7 +102,7 @@ Now let's try applying some entries: ...@@ -103,7 +102,7 @@ Now let's try applying some entries:
>>> root['sally-balance'] >>> root['sally-balance']
-80.0 -80.0
If we give provide entries that cause an unexpected error: If we provide entries that cause an unexpected error:
>>> apply_entries([ >>> apply_entries([
... ('bob', 10.0), ... ('bob', 10.0),
......
...@@ -18,13 +18,12 @@ Applications ...@@ -18,13 +18,12 @@ Applications
To demonstrate how savepoints work with transactions, we've provided a To demonstrate how savepoints work with transactions, we've provided a
sample data manager implementation that provides savepoint support. sample data manager implementation that provides savepoint support.
The primary purpose of this data manager is to provide code that can The primary purpose of this data manager is to provide code that can
be read to understand how savepoints work. The secondary purpose is to be read to understand how savepoints work. The secondary purpose is to
provide support for demonstrating the correct operation of savepoint provide support for demonstrating the correct operation of savepoint
support within the transaction system. This data manager is very support within the transaction system. This data manager is very
simple. It provides flat storage of named immutable values, like strings simple. It provides flat storage of named immutable values, like strings
and numbers. and numbers.
>>> import transaction.tests.savepointsample >>> import transaction.tests.savepointsample
>>> dm = transaction.tests.savepointsample.SampleSavepointDataManager() >>> dm = transaction.tests.savepointsample.SampleSavepointDataManager()
>>> dm['name'] = 'bob' >>> dm['name'] = 'bob'
...@@ -44,13 +43,13 @@ and abort changes: ...@@ -44,13 +43,13 @@ and abort changes:
>>> dm['name'] >>> dm['name']
'bob' 'bob'
Now, lets look at an application that manages funds for people. Now, let's look at an application that manages funds for people.
It allows deposits and debits to be entered for multiple people. It allows deposits and debits to be entered for multiple people.
It accepts a sequence of entries and generates a sequence of status It accepts a sequence of entries and generates a sequence of status
messages. For each entry, it applies the change and then validates messages. For each entry, it applies the change and then validates
the user's account. If the user's account is invalid, we role back the user's account. If the user's account is invalid, we roll back
the change for that entry. The success or failure of an entry is the change for that entry. The success or failure of an entry is
indicated in the output status. First we'll initialize some accounts: indicated in the output status. First we'll initialize some accounts:
>>> dm['bob-balance'] = 0.0 >>> dm['bob-balance'] = 0.0
>>> dm['bob-credit'] = 0.0 >>> dm['bob-credit'] = 0.0
...@@ -65,8 +64,7 @@ Now, we'll define a validation function to validate an account: ...@@ -65,8 +64,7 @@ Now, we'll define a validation function to validate an account:
... raise ValueError('Overdrawn', name) ... raise ValueError('Overdrawn', name)
And a function to apply entries. If the function fails in some And a function to apply entries. If the function fails in some
unexpected way, it rolls back all of it's changes and unexpected way, it rolls back all of its changes and prints the error:
prints the error:
>>> def apply_entries(entries): >>> def apply_entries(entries):
... savepoint = transaction.savepoint() ... savepoint = transaction.savepoint()
...@@ -108,7 +106,7 @@ Now let's try applying some entries: ...@@ -108,7 +106,7 @@ Now let's try applying some entries:
>>> dm['sally-balance'] >>> dm['sally-balance']
-80.0 -80.0
If we give provide entries that cause an unexpected error: If we provide entries that cause an unexpected error:
>>> apply_entries([ >>> apply_entries([
... ('bob', 10.0), ... ('bob', 10.0),
...@@ -160,7 +158,7 @@ Once a savepoint has been used, it can't be used again: ...@@ -160,7 +158,7 @@ Once a savepoint has been used, it can't be used again:
... ...
InvalidSavepointRollbackError InvalidSavepointRollbackError
Using a savepoint also invalidates any savepoints that com eafter it: Using a savepoint also invalidates any savepoints that come after it:
>>> savepoint1 = transaction.savepoint() >>> savepoint1 = transaction.savepoint()
>>> dm['bob-balance'] = 100.0 >>> dm['bob-balance'] = 100.0
...@@ -202,8 +200,8 @@ support savepoints: ...@@ -202,8 +200,8 @@ support savepoints:
However, a flag can be passed to the transaction savepoint method to However, a flag can be passed to the transaction savepoint method to
indicate that databases without savepoint support should be tolerated indicate that databases without savepoint support should be tolerated
until a savepoint is roled back. This allows transactions to proceed until a savepoint is rolled back. This allows transactions to proceed
is there are no reasons to roll back: if there are no reasons to roll back:
>>> dm_no_sp['name'] = 'sally' >>> dm_no_sp['name'] = 'sally'
>>> savepoint = transaction.savepoint(1) >>> savepoint = transaction.savepoint(1)
...@@ -228,7 +226,7 @@ uncommitable. From that point on, most transaction operations, ...@@ -228,7 +226,7 @@ uncommitable. From that point on, most transaction operations,
including commit, will fail until the transaction is aborted. including commit, will fail until the transaction is aborted.
In the previous example, we got an error when we tried to rollback the In the previous example, we got an error when we tried to rollback the
savepoint. If we try to commit the transaction, the commit will fail: savepoint. If we try to commit the transaction, the commit will fail:
>>> transaction.commit() # doctest: +ELLIPSIS >>> transaction.commit() # doctest: +ELLIPSIS
Traceback (most recent call last): Traceback (most recent call last):
......
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