Enhance the comments in the templatevtab.c implementation.

FossilOrigin-Name: 05f6278a02e5cde89f76ced5af7d508e26576d7291dad7ee9e06b1a3be516cb0

ext/misc/templatevtab.c

@@ -10,40 +10,45 @@
 **
 *************************************************************************
 **
-** This file implements a template virtual-table implementation.
+** This file implements a template virtual-table.
 ** Developers can make a copy of this file as a baseline for writing
 ** new virtual tables and/or table-valued functions.
 **
 ** Steps for writing a new virtual table implementation:
 **
-**     (1)  Make a copy of this file.  Prehaps "mynewvtab.c"
+**     (1)  Make a copy of this file.  Perhaps call it "mynewvtab.c"
 **
 **     (2)  Replace this header comment with something appropriate for
 **          the new virtual table
 **
 **     (3)  Change every occurrence of "templatevtab" to some other string
 **          appropriate for the new virtual table.  Ideally, the new string
-**          should be the basename of the source file: "mynewvtab".
+**          should be the basename of the source file: "mynewvtab".  Also
+**          globally change "TEMPLATEVTAB" to "MYNEWVTAB".
 **
 **     (4)  Run a test compilation to make sure the unmodified virtual
 **          table works.
 **
-**     (5)  Begin making changes to make the new virtual table do what you
-**          want it to do.
-**
-**     (6)  Ensure that all the "FIXME" comments in the file have been dealt
-**          with.
+**     (5)  Begin making incremental changes, testing as you go, to evolve
+**          the new virtual table to do what you want it to do.
 **
 ** This template is minimal, in the sense that it uses only the required
 ** methods on the sqlite3_module object.  As a result, templatevtab is
 ** a read-only and eponymous-only table.  Those limitation can be removed
 ** by adding new methods.
+**
+** This template implements an eponymous-only virtual table with a rowid and
+** two columns named "a" and "b".  The table as 10 rows with fixed integer
+** values. Usage example:
+**
+**     SELECT rowid, a, b FROM templatevtab;
 */
 #if !defined(SQLITEINT_H)
 #include "sqlite3ext.h"
 #endif
 SQLITE_EXTENSION_INIT1
 #include <string.h>
+#include <assert.h>
 
 /* templatevtab_vtab is a subclass of sqlite3_vtab which is
 ** underlying representation of the virtual table
@@ -92,6 +97,9 @@ static int templatevtabConnect(
   rc = sqlite3_declare_vtab(db,
            "CREATE TABLE x(a,b)"
        );
+  /* For convenience, define symbolic names for the index to each column. */
+#define TEMPLATEVTAB_A  0
+#define TEMPLATEVTAB_B  1
   if( rc==SQLITE_OK ){
     pNew = sqlite3_malloc( sizeof(*pNew) );
     *ppVtab = (sqlite3_vtab*)pNew;
@@ -151,7 +159,15 @@ static int templatevtabColumn(
   int i                       /* Which column to return */
 ){
   templatevtab_cursor *pCur = (templatevtab_cursor*)cur;
-  sqlite3_result_int(ctx, (i+1)*1000 + pCur->iRowid);
+  switch( i ){
+    case TEMPLATEVTAB_A:
+      sqlite3_result_int(ctx, 1000 + pCur->iRowid);
+      break;
+    default:
+      assert( i==TEMPLATEVTAB_B );
+      sqlite3_result_int(ctx, 2000 + pCur->iRowid);
+      break;
+  }
   return SQLITE_OK;
 }
 

manifest

@@ -1,5 +1,5 @@
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-D 2018-04-26T18:34:26.853
+C Enhance\sthe\scomments\sin\sthe\stemplatevtab.c\simplementation.
+D 2018-04-27T15:17:08.924
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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 F Makefile.in 5ce9343cba9c189046f1afe6d2bcc1f68079439febc05267b98aec6ecc752439
@@ -297,7 +297,7 @@ F ext/misc/showauth.c 732578f0fe4ce42d577e1c86dc89dd14a006ab52
 F ext/misc/spellfix.c 54d650f44f3a69a851814791bd4d304575cdbbf78d96d4f0801b44a8f31a58c5
 F ext/misc/sqlar.c 57d5bc45cd5492208e451f697404be88f8612527d64c9d42f96b325b64983d74
 F ext/misc/stmt.c 6f16443abb3551e3f5813bb13ba19a30e7032830015b0f92fe0c0453045c0a11
-F ext/misc/templatevtab.c 52b9363de0ae4a695728a52769a2e2dab8a0a2db77ca753ad9e1a0d0f32d1f89
+F ext/misc/templatevtab.c 8251b31011dd00fc38e739c78c234c930be42b3b274bbe0493b79cd40db02a9e
 F ext/misc/totype.c 4a167594e791abeed95e0a8db028822b5e8fe512
 F ext/misc/unionvtab.c 0b3173f69b8899da640a13a345dc5ef1400199405f738abe6145b2454195b8ff
 F ext/misc/vfslog.c fe40fab5c077a40477f7e5eba994309ecac6cc95
@@ -1725,7 +1725,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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-P 0fcfc36ceb820fc70136b799a0405fe92e50646e697be2872bbe9a53a05ed5a9
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+R 408ce2695c1a501e1640fcd4bee57806
 U drh
-Z f084b8f7ac201c9b316a44eacae3d476
+Z 4384bff1ecbee30802e6ddd37b479122

manifest.uuid

@@ -1 +1 @@
-9fd0faf517993587d2f54212638545fc85fbbc84a031bcfae8c1e5894825d83b
+05f6278a02e5cde89f76ced5af7d508e26576d7291dad7ee9e06b1a3be516cb0