Have you ever hunted around a directory for a file ... you KNOW it's there, but you can't find it - can't see the wood for the trees, if you like, in a listing that spills over many pages?
I call such directory structures "pancakes" as they're thin and flat, and they tend not to be very easy to work with as they grow and grow. It's usually best to avoid a pancake if you can - either set up a directory structure if you require ad-hoc access to all the various different data pieces, or use a database such as MySQL to hold the data ... this is the technique we're using for images in our database, as described in the current edition of "Of Course".
The Authors of Tcl had an issue with a pancake of commands that could have been provided in the language, so that came us with a hierarchy of commands and subcommands. Within a top level around a hundred top level commands, you'll find commands that have subcommand in particular areas such as
string - most commands to do with string handling
file - most commands to do with file handling
array - all commands to do with array handling
clock - all commands to do with time handling
info - commands that provide information
(written 2006-06-26 18:09:20)
Associated topics are indexed under
T205 - Tcl/Tk - String Handling in Tcl [2472] split and join in tcl and expect - (2009-10-23)
[1601] Replacing the last comma with an and - (2008-04-04)
[1410] Tcl / regsub - changing a string and using interesting bits - (2007-10-27)
[1403] Square Bracket protection in Tcl - (2007-10-23)
[943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
[404] How to check that a string contains a number in Tcl - (2005-08-06)
T208 - Tcl/Tk - Arrays [2466] Tcl - passing arrays and strings in and back out of procs - (2009-10-22)
[1614] When an array is not an array - (2008-04-17)
[1427] Arrays in Tcl - a demonstration - (2007-11-10)
[1405] Sorting in Tcl - lists and arrays - (2007-10-24)
[1283] Generating traffic for network testing - (2007-07-29)
[1282] Stringing together Tcl scripts - (2007-07-29)
[122] Passing arrays to procs in Tcl - (2004-11-18)
T209 - Tcl/Tk - File and Directory Handling [2467] Tcl - catching an error before your program crashes - (2009-10-22)
[1467] stdout v stderr (Tcl, Perl, Shell) - (2007-12-10)
[1426] Buffering up in Tcl - the empty coke can comparison - (2007-11-10)
[1407] Reading from another process in Tcl (pipes and sockets) - (2007-10-26)
[785] Running external processes in Tcl and Tcl/Tk - (2006-06-29)
Some other Articles
Good follow up ... my thanksConverting between Hex and Decimal in TclTcl - lappend v concatSeparation and IntegrationThe fragility of pancakes - and better structuresWeekend in IrelandOn Crosby sandsNaming RoomsDo not duplicate your codeBed and Breakfast, or Hotel?