From ff82ad268fce08e7859ca5bd1d4ef68593c23f0f Mon Sep 17 00:00:00 2001 From: Marcus Boerger Date: Fri, 2 May 2003 03:09:58 +0000 Subject: [PATCH] Add some info --- ext/spl/README | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100755 ext/spl/README diff --git a/ext/spl/README b/ext/spl/README new file mode 100755 index 0000000000..e4d9aaf7a2 --- /dev/null +++ b/ext/spl/README @@ -0,0 +1,39 @@ +
+This is an extension that aims to implement some efficient data access 
+interfaces and classes.
+
+SPL allows to hook into foreach. Doing so you can do something like
+this:
+
+	$obj = new whatever();
+	foreach($obj as $key => $value) { ... }
+
+This is meant to be used for database access. For example you could
+grab my patch to sqlite (http://marcus-boerger.de/php/ext/sqlite/) and
+look at the oo tests:
+
+	$db = new sqlite($filename);
+	foreach($db->query("SELECT....") as $row) { ... }
+
+SQLite offers four access strategies:
+1) sqlite_query + sqlite_fetch_array
+2) sqlite_unbuffered_query + sqlite_fetch_array
+3) sqlite_query + iterators (sqlite_current)
+4) sqlite_unbuffered_query + iterators (sqlite_current)
+
+1) and 3) do "over eager evaluating" since they fetch all rows directly.
+
+2) does "eager evaluating". It always fetches the next row but doesn't 
+keep the current row, so that it must be stored elsewhere if it must be 
+accessed more then once. For instance this happens when you need to access 
+columns separately.
+
+4) does "eager evaluating". But in contrast to 2) it keeps the current row
+hence its name.
+
+There is no efficient way for "lazy or just in time evaluating" so 4) should 
+be the best case. And 4) also enables the foreach trick.
+
+To implement 3) and 4) with other db extensions ask me and wait for LT to pass.
+
+
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