Tcl
Tcl (pronounced "tickle" or tee cee ell /ˈtiː siː ɛl/) or Tool Command Language is a High-level programming language which can be used for many things. Tcl was made to be easy to use, but able to do many things.[5] Tcl's language is based on commands which tell the computer what to do or how to save a variable. Tcl is able to do object-oriented, imperative, functional, or procedural styles.
Paradigm(s) | multi-paradigm: object-oriented, functional, procedural, event-driven programming, imperative |
---|---|
Appeared in | 1988 |
Designed by | John Ousterhout |
Developer | Tcl Core Team |
Stable release | 8.6.8 (Dec, 22 2017) / December 22, 2017 |
Typing discipline | dynamic typing, everything can be treated as a string |
Major implementations | ActiveTcl Androwish |
Dialects | Jim |
Influenced by | AWK, Lisp |
Influenced | PHP,[1] Tea, PowerShell[2] |
License | BSD-style[3] |
Usual filename extensions | .tcl, .tbc[4] |
Website | www |
Tcl is used a lot to in C to create prototypes quickly.[6] There are interpreters available for many operating systems. This means many different kinds of computers are able to run Tcl code. Tcl is a very small language which means it is good to use as embedded systems.
Tcl is sometimes combined with Tk. When it is, it is called Tcl/Tk. Tcl/Tk is a part of the normal Python installation.
History
Tcl was created by John Ousterhout at University of California, Berkeley.[7][8] Ousterhout won a ACM Software System Award in 1997 for making Tcl/Tk.[9]
Safe-Tcl is a form of Tcl that has certain parts turned off so it can't hurt the computer which is running it. Nathaniel Borenstein and Marshall Rose created Safe-Tcl. Safe-Tcl can only work on some files including email messages.
Examples
In Tcl programming, empty whitespace separates words. Commands are ended by going to a new line or a semicolon:
word0 word1 word2 ... wordN
The first word is always a command which comes from Tcl's library:
commandName arg1 arg2 ... argN
For example, the commmand puts makes the computer display something:
<source lang=Tcl> puts "Hello, World!" </source>
In that example, "Hello, World!" is called a string. Tcl adds a special character which can't be seen at the end of a line. This character tells the computer to go a new line after the command is complete.
Tcl is able to do math and many other things using variables. In order to use a variable, the programmer must set their value:
<source lang=Tcl> set variableA 1 set variableB 2 </source>
After a variable is set, it can be used in other parts of the program or set to something different. Variables can be used to perform math:
<source lang=Tcl> set x 2 set y 4 set ans [expr $x+$y] puts "The answer is $ans." # The computer would show: "The answer is 6." </source>
The command expr tells the computer to solve the "expression" or, in this case, an equation.
Easy commands
set
saves numbers, words, or letters, to a variable. It can also be used to change what is in a variable.proc
tells the computer what a new command will do (procedure).if
tells the computer to do what is written only if something is true.while
tells the computer to do what is written as long as something is true.foreach
tells the computer to something for each item in a list of variables.break
stops the command from running. This is good to use to get out of a loop.continue
stops the active command, but allows the loop to continue. If the loop is awhile
loop, it will start over. It will letforeach
andfor
go to the next step in the program.return
stops the active command and loop, then goes back to the procedure with a value.
Related pages
References
- ↑ Lerdorf, Rasmus (2007-04-26). "PHP on Hormones – history of PHP presentation by Rasmus Lerdorf given at the MySQL Conference in Santa Clara, California". The Conversations Network. Retrieved 2009-12-11.
- ↑ "Windows PowerShell : PowerShell and WPF: WTF". Archived from the original on 2008-12-25. Retrieved 2018-09-25.
- ↑ "Tcl/Tk License Terms". Tcl Developer Xchange. Retrieved 2016-11-02.
- ↑ "Tcl Dev Kit - Compiler". ActiveState Docs. Archived from the original on 2016-10-20. Retrieved 2016-11-02.
- ↑ "Language". Tcl Developer Xchange. Retrieved 2016-11-02.
- ↑ "Uses for Tcl/Tk". Tcl Developer Xchange. Retrieved 2016-11-02.
- ↑ John Ousterhout. "History of Tcl". Personal pages. Stanford University. Retrieved 2011-08-09.
- ↑ "History of Tcl". Tcl Developer Xchange. Retrieved 2016-11-02.
- ↑ "John K Ousterhout - Award Winner". ACM Awards. Retrieved 2016-11-04.
Other websites
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