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authorAndrew M. Kuchling <amk@amk.ca>2006-09-12 21:09:02 (GMT)
committerAndrew M. Kuchling <amk@amk.ca>2006-09-12 21:09:02 (GMT)
commit32cec80b0219ff9e0b52baa3580878103af722d3 (patch)
tree27ee9cbb6b706e0b12d3c5974cf960d44fdfbdad /Doc
parentabd5520cff4404929440d51fff808dee4560584e (diff)
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Some editing, markup fixes
Diffstat (limited to 'Doc')
-rw-r--r--Doc/lib/libsqlite3.tex47
1 files changed, 24 insertions, 23 deletions
diff --git a/Doc/lib/libsqlite3.tex b/Doc/lib/libsqlite3.tex
index 45e67f7..1afb5d7 100644
--- a/Doc/lib/libsqlite3.tex
+++ b/Doc/lib/libsqlite3.tex
@@ -464,20 +464,19 @@ This is how SQLite types are converted to Python types by default:
\lineii{BLOB}{buffer}
\end{tableii}
-The type system of the \module{sqlite3} module is extensible in both ways: you can store
+The type system of the \module{sqlite3} module is extensible in two ways: you can store
additional Python types in a SQLite database via object adaptation, and you can
let the \module{sqlite3} module convert SQLite types to different Python types via
converters.
\subsubsection{Using adapters to store additional Python types in SQLite databases}
-Like described before, SQLite supports only a limited set of types natively. To
+As described before, SQLite supports only a limited set of types natively. To
use other Python types with SQLite, you must \strong{adapt} them to one of the sqlite3
-module's supported types for SQLite. So, one of NoneType, int, long, float,
+module's supported types for SQLite: one of NoneType, int, long, float,
str, unicode, buffer.
-The \module{sqlite3} module uses the Python object adaptation, like described in PEP 246
-for this. The protocol to use is \class{PrepareProtocol}.
+The \module{sqlite3} module uses Python object adaptation, as described in \pep{246} for this. The protocol to use is \class{PrepareProtocol}.
There are two ways to enable the \module{sqlite3} module to adapt a custom Python type
to one of the supported ones.
@@ -493,8 +492,8 @@ class Point(object):
self.x, self.y = x, y
\end{verbatim}
-Now you want to store the point in a single SQLite column. You'll have to
-choose one of the supported types first that you use to represent the point in.
+Now you want to store the point in a single SQLite column. First you'll have to
+choose one of the supported types first to be used for representing the point.
Let's just use str and separate the coordinates using a semicolon. Then you
need to give your class a method \code{__conform__(self, protocol)} which must
return the converted value. The parameter \var{protocol} will be
@@ -507,13 +506,13 @@ return the converted value. The parameter \var{protocol} will be
The other possibility is to create a function that converts the type to the
string representation and register the function with \method{register_adapter}.
- \verbatiminput{sqlite3/adapter_point_2.py}
-
\begin{notice}
The type/class to adapt must be a new-style class, i. e. it must have
\class{object} as one of its bases.
\end{notice}
+ \verbatiminput{sqlite3/adapter_point_2.py}
+
The \module{sqlite3} module has two default adapters for Python's built-in
\class{datetime.date} and \class{datetime.datetime} types. Now let's suppose
we want to store \class{datetime.datetime} objects not in ISO representation,
@@ -523,16 +522,17 @@ but as a \UNIX{} timestamp.
\subsubsection{Converting SQLite values to custom Python types}
-Now that's all nice and dandy that you can send custom Python types to SQLite.
+Writing an adapter lets you send custom Python types to SQLite.
But to make it really useful we need to make the Python to SQLite to Python
-roundtrip work.
+roundtrip work.
Enter converters.
-Let's go back to the Point class. We stored the x and y coordinates separated
-via semicolons as strings in SQLite.
+Let's go back to the \class{Point} class. We stored the x and y
+coordinates separated via semicolons as strings in SQLite.
-Let's first define a converter function that accepts the string as a parameter and constructs a Point object from it.
+First, we'll define a converter function that accepts the string as a
+parameter and constructs a \class{Point} object from it.
\begin{notice}
Converter functions \strong{always} get called with a string, no matter
@@ -558,11 +558,12 @@ database is actually a point. There are two ways of doing this:
\item Explicitly via the column name
\end{itemize}
-Both ways are described at \ref{sqlite3-Module-Contents} in the text explaining
-the constants \constant{PARSE_DECLTYPES} and \constant{PARSE_COlNAMES}.
+Both ways are described in section~\ref{sqlite3-Module-Contents}, in
+the text explaining the constants \constant{PARSE_DECLTYPES} and
+\constant{PARSE_COLNAMES}.
-The following example illustrates both ways.
+The following example illustrates both approaches.
\verbatiminput{sqlite3/converter_point.py}
@@ -571,8 +572,8 @@ The following example illustrates both ways.
There are default adapters for the date and datetime types in the datetime
module. They will be sent as ISO dates/ISO timestamps to SQLite.
-The default converters are registered under the name "date" for datetime.date
-and under the name "timestamp" for datetime.datetime.
+The default converters are registered under the name "date" for \class{datetime.date}
+and under the name "timestamp" for \class{datetime.datetime}.
This way, you can use date/timestamps from Python without any additional
fiddling in most cases. The format of the adapters is also compatible with the
@@ -584,12 +585,12 @@ The following example demonstrates this.
\subsection{Controlling Transactions \label{sqlite3-Controlling-Transactions}}
-By default, the \module{sqlite3} module opens transactions implicitly before a DML
-statement (INSERT/UPDATE/DELETE/REPLACE), and commits transactions implicitly
-before a non-DML, non-DQL statement (i. e. anything other than
+By default, the \module{sqlite3} module opens transactions implicitly before a Data Modification Language (DML)
+statement (i.e. INSERT/UPDATE/DELETE/REPLACE), and commits transactions implicitly
+before a non-DML, non-query statement (i. e. anything other than
SELECT/INSERT/UPDATE/DELETE/REPLACE).
-So if you are within a transaction, and issue a command like \code{CREATE TABLE
+So if you are within a transaction and issue a command like \code{CREATE TABLE
...}, \code{VACUUM}, \code{PRAGMA}, the \module{sqlite3} module will commit implicitly
before executing that command. There are two reasons for doing that. The first
is that some of these commands don't work within transactions. The other reason