GEB—SQLite in Tcl in SQLite

A Tcl/Tk script for displaying and maintaining an SQLite database, stored in an SQLite database

GEB—Presentation Overview

● How the project started● What its goals have been● Early version● Evolution: tkTable, storing script in SQLite, etc.● Bootup summary● Past and future● Potential users and licensing● Live demonstration

GEB: (evolving) Design Goals

● Reduce dependence on proprietary s/w and data formats (MS Access, dBase n)

● Convenient scripting language, run on Linux and Windows

● Develop single package for all my needs– View table/column names

– View and edit table contents

– Store/edit/execute Tcl/SQL code in the database

– Store the program itself in the database

– Add functions as the need arises (ongoing)

GEB: Design Drivers

● Develop incrementally● Keep data safe

– Show generated SQL before COMMITting– Disallow many combinations of Alter Table

functions in a single pass– Accept slower screen updates

● Easy to use● Minimize bootstrap

GEB: Pre-Tktable (top)

GEB: Pre-Tktable (bottom)

GEB: Alter Table

GEB: Pre-Tktable (edittable)

GEB: Change to Tktable

● Driven by desire to improve looks● Each table is editable, in its own window● Solved potential problem of displaying large

databases– Each cell entry value from an individual SELECT

● Safe but slower● Neither specific potential problem nor iron-clad

bulletproofing has been found

GEB: Main window

GEB: Table Display

GEB: Stand-alone Functions

● Convert between v2 and v3 file formats● Import table from or export table to delimited file

– First row can be column names or data– Imported data can have variable number of

columns● Import db element from or export db element to

text file (like ONECOLUMN method)● Execute a single line of SQL or Tcl

GEB: Run SQL

GEB: Decision to Put showtable in Database File

● Inspired by the “Database as Program” section of DRH's “SQLite and Tcl” paper, but not an implementation of it

● I wanted to put a functional block (the chief proc for a function and its supporting proc's) in one table– Can't put header and body in separate columns– Outside function can't call support proc unless its

functional block is known to have been loaded

GEB: Impacts of Putting showtable in Database File

● ATTACH capability became mandatory– If only one file can be displayed/edited, that one slot

can't be taken up by the displaying program itself– Redo data arrays as 2D (attach name and original

index)● Had to implement editor

– Searching routine needed to look at all Tcl tables– Find matching brackets, braces, and parentheses– Replace and Replace All, with and without

confirmation required● Check for infinite loop

GEB: editruntcl

GEB: search

GEB: Bootstrap● package require Tk; package require Tktable; console show

● # Create namespace for all "globals" and procs

● namespace eval ::GEB {}

● load /sqlite/tclsqlite3.dll

● load /sqlite/tclsqlite.dll

● set dbfile showtable.sq3

● sqlite3 sq $dbfile

● set ::GEB::attachfilename(main) $dbfile

● proc evalsqlitetcl table {

● uplevel #0 [join [sq eval "select tcl from $table limit 1"]]

● }

● evalsqlitetcl main_attach

● editruntcl

● # attachit s2008 /irisdata/2008symp/2008symp.sq3

GEB: main_attach Overview

● Read in core routines– Those needed before “unknown” is set up

● Set up window and arrays for main file– Table names, columns in each table, etc.

● Extend “unknown” proc handler to look in database file– If a table with the name of the needed proc exists,

load it– If the loading defines the proc, execute it– Otherwise, exec original “unknown” handler

GEB: Summary of Development Experience

● Amazingly few gotchas considering my level of knowledge of Tcl/Tk/SQLite when I started

● It often took longer to decide what I wanted to do and how I wanted it to work than to implement it.

● A very useful tool. For me. It fits my way of thinking. But for others it may be too idiosyncratic.

GEB: Future Plans

● Allow wildcards in searches● Allow editing a development version while

executing stable version (row vs column)● Switch to Tile● Implement full text search support● Facilitate displays of views● ....

GEB: Potential Users

● One extreme: Tcl developer who does not care about SQLite– Conceivable, but many more facilities available

elsewhere● Other extreme: SQLite user who does not care

about Tcl– Slightly more reasonable, but again, other tools

available● Happy medium: User with some data and some

scripts, who wants to keep and use them together

GEB: Licensing● Intended to be released to Public Domain

– (It would feel wrong to be more restrictive than SQLite itself)

– SQLite blessing or equivalent:● May you do good and not evil● May you find forgiveness for yourself and forgive others● May you share freely, never taking more than you give

● Further development encouraged, especially if kept public

● Support available--inquire within– Gerry Snyder mesmerizerfan@gmail.com