What is it?
Sometimes classed as a client-side web programming language
along with
Javascript,
Jscript and VBscript,
TCL has a far wider range of uses, particularly in application
integration, and it is possibly the most widely adopted language
for automated hardware and software testing.
TCL is free to download. It can be used to create cross-platform
applications. TCL and its graphical user interface tool, TK, take
care of platform-specific issues, such as look and feel. The
language is very extensible potentially, any application developed
in TCL can add functionality to the language.
For users who are wary of open source, TCL is available in a
commercial distribution with full service and support. ActiveTCL
from ActiveState is described as "the industry-standard TCL
distribution".
Where did it originate?
John Ousterhout began working on TCL at Berkeley in 1987. His
aim was to create an embeddable command language, and he had three
specific goals: it must be simple and generic, so that it could
work easily with many different applications it must be easy for
each application to add its own features to the language and, since
most functionality would come from applications, TCL would
integrate or "glue together" the extensions.
In 1994, Ousterhout joined
Sun, where TCL/TK was seen as "the perfect complement to Java
for scripting and system integration". In 2000, the TCL Core Team
was formed to take responsibility for development away from any
single commercial organisation.
What's it for?
TCL is most commonly used for rapid prototyping, scripted
applications, graphical user interfaces, testing using the "TCL
test" framework, and CGI scripting. A small-footprint form of the
language is used for embedded systems work.
TCL has a simple syntax, which makes code easy to write and to
maintain. According to the official TCL website, www.tcl.tk, "TCL
scripts are often more compact and readable than functionally
equivalent code in other languages."
TCL is extensible with C, C++ and Java, as well as itself, and
it has extensions for
MySQL,
Oracle,
Sybase,
PostgreSQL, Berkeley DB, SQLite and ODBC-compliant databases.
Recent versions include object-oriented extensions.
What makes it special?
Portability and speed of development, with supporters claiming
TCL can be five to 10 times faster than other languages,
particularly for applications involving graphical interfaces.
Ousterhout says, "Many TCL users assert that TK is the only
reason they use TCL. Some of them do not even like TCL and wish
that TK could be mated with a different scripting language. In
fact, this has happened several times, including TKPerl and
Python."
How difficult is it to master?
For such a powerful language used by "elite" programmers, TCL
has a simple syntax, which is applied in a consistent way. It is
sometimes used as an introduction to programming for students.
Where is it used?
TCL is used widely by software and networking suppliers and by
end-user organisations, including AOL, Shell, broadcasters and
defence and aerospace companies. The TCL website says Oracle,
Sybase and Cisco "have millions of lines of TCL testing code".
What systems does it run on?
Windows, Macintosh, Linux and most flavours of Unix. About
two-thirds of downloads of TCL are thought to be for use with
Windows.
Training
Tutorials, downloads and links to TCL code resources are
available online. The standard ActiveTCL distribution is also
available for download.
Rates of pay
Developers with TCL skills plus Java or C++ can earn £25,000 to
£36,000. TCL contract test engineers can earn £40 to £45 an
hour.
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