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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Buffering up in Tcl - the empty coke can comparison

A comment on buffering in Tcl ....

if {1 == 0} {
When you finish drinking a can of Coke, you don't call
your local recycling plant up straight away and have them
send a truck around to collect the empty - that would be
inefficient to put it mildly. And in the same way,
a computer doesn't always save its output character by
character to the disc or screen - rather it buffers it up.
In most languages a clever strategy controls when the buffer
really is written (flushed) so that it's not very common for
the programmer to have to add an explicit flush request.
 
With Tcl, the default is that the output buffer flushes
each time it receives a new line character, which works
well enough most of the time. However, there are occasions
that you'll want to use the -nonewline option to puts to
allow you to generate a prompt and leave the cursor hanging
on the same line awaiting input from the user, and in such
cases you'll need an extra flush command.
}
 
puts -nonewline "How old are you "
flush stdout
set age [gets stdin]
puts "You are $age years old then"
 
if {1 == 0} {
Where you have multiple user inputs, you may prefer to
use a proc to read inputs and encapsulate the flush within
it, or you may prefer to run
 
fconfigure stdout -buffering none
 
which (technically) turns autoflush mode on rather than
turning buffering off!
}


If you want to comment a whole block of code .... you might like to use my little trick of testing for the impossible - "1 == 0" in the above - which lets you put code aside neatly, cleanly and nested. You'll see that I've even used it to provide documentation for today's entry ...
(written 2007-11-10)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
T209 - Tcl/Tk - File and Directory Handling
  [779] The fragility of pancakes - and better structures - (2006-06-26)
  [785] Running external processes in Tcl and Tcl/Tk - (2006-06-29)
  [1407] Reading from another process in Tcl (pipes and sockets) - (2007-10-26)
  [1467] stdout v stderr (Tcl, Perl, Shell) - (2007-12-10)
  [2467] Tcl - catching an error before your program crashes - (2009-10-22)
  [3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04)
  [3320] Reading the nth line from a file (Perl and Tcl examples) - (2011-06-09)
  [3429] Searching through all the files in or below a directory - Ruby, Tcl, Perl - (2011-09-09)
  [3617] The fileutil package and a list of file system commands in Tcl - (2012-02-18)
  [4461] Reading from a URL, and reading Json, from your Tcl script - (2015-03-12)
  [4523] Catching failed commands and not crashing the program in Tcl - (2015-10-10)
  [4524] Tcl - a new example for data reformatting - (2015-10-10)

T202 - Tcl/Tk - Tcl Fundamentals
  [3] Looking for a donkey - (2004-08-05)
  [210] Joining lists in Tcl. Indirect variables in Tcl. - (2005-02-12)
  [328] Making programs easy for any user to start - (2005-05-29)
  [349] Comments in Tcl - (2005-06-16)
  [362] The ireallyreallywanna operator - (2005-06-28)
  [782] Converting between Hex and Decimal in Tcl - (2006-06-28)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1282] Stringing together Tcl scripts - (2007-07-29)
  [1469] Curley brackets v double quotes - Tcl, Tk, Expect - (2007-12-12)
  [2442] Variable storage - Perl, Tcl and Python compared - (2009-10-08)
  [3917] BODMAS - the order a computer evaluates arithmetic expressions - (2012-11-09)
  [4324] Learning to program - variables and constants - (2014-11-22)
  [4453] Tcl variable names - no real limits! - (2015-03-10)


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Arrays in Tcl - a demonstration
Some other Articles
Integer v float - Python
Remembrance day - inside a church and inside the day
Travel Across Wiltshire - the game
Arrays in Tcl - a demonstration
Buffering up in Tcl - the empty coke can comparison
Melksham v Ely
Closer than you think - the next step
MySQL - table design and initial testing example
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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