Yabasic running an implementation of SameGame. |
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| Developer(s) | Marc-Oliver Ihm (ret.) Pedro Sá Thomas Larsen |
|---|---|
| Stable release | 2.763 / August, 2007 |
| Operating system | Windows, Unix |
| Type | Programming |
| License | GNU General Public License version 3 or later |
| Website | www.yabasic.de - original version to V 2.763 yabasic.basicprogramming.org - version 3 |
Yabasic (Yet Another BASIC) is a free and open source BASIC interpreter for Windows and Unix platforms.[1] Yabasic was originally developed by Marc-Oliver Ihm, who released the last stable version 2.763 in 2005. As a continuation of the project, version 3 is now developed by a team centered around Pedro Sá and Thomas Larsen. The Yabasic interpreter is quite compact at about 250 kilobytes total.
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Yabasic started as a very simple interpreter around May 1995. When it was released as version 1.0 it lacked many features like arrays and loops. In summer 1996, Yabasic was ported to the Win32 platform (Version 2.0). Further improvements were the addition of subroutines and libraries (summer 1999, version 2.57), and graphic capabilities.
In August 2007, Ihm stated that "probably (he) will not develop Yabasic any further (beyond version 2.763) within the foreseeable future", due to a lack of time. Sá and Larsen have revived the project, and currently work on Yabasic 3,[2] and on releasing bugfixes for version 2.763.[3] Several beta releases of version 3 have been released since December 2009.[4]
Passing of arguments is always by value, except for arrays, which are always passed by reference.
The interpreter is very lenient in syntactical matters—for example, both color and colour are legal variants for the same command. Likewise, there are a number of different versions for if and for constructs, giving the programmer freedom of choice in their design.
The most significant change from version 2 to version 3 is the introduction of user-defined data types.[5]
Yabasic's idiosyncratic way of accessing system variables with peek and poke-commands has been dropped in favour of reserved variable names. Old-style BASIC control flow features (goto, gosub, labels) are no longer supported. Declaration of variables prior to use can optionally be enforced.
The classic Hello World program looks like this in Yabasic,
print "Hello World"
The following example will calculate prime numbers,
print "This program will calculate the prime numbers below the limit"
input "limit: " limit
n=2
do
for i=2 to sqrt(n)
if (frac(n/i)=0) then
notprime=1
break
endif
next i
if notprime<>1 then
print n
endif
notprime=0
n=n+1
if n>limit break
loop
String variables can be compiled into program code at runtime, allowing for self-modifying code.
For example, the sequence
x$= "sub printme() \n print \"Hello world!\" \n end sub" compile(x$)
would create a new procedure,
sub printme() print "Hello world!" end sub
while the program is running. This procedure can from this point on be invoked in either the 'traditional' way,
printme()
or via the slightly more clever:
y$= "printme()" execute(y$)
A port of Yabasic to the Fltk toolkit called "Flyab" was under development. It would have been source-compatible with programs written in yab, a variant of Yabasic that enables graphical programs to e written using the BeOS API. Ports for Windows, Mac OS X, and Linux were planned. Flyab added the ability to Yabasic to create native graphical user interfaces on all supported platforms. As of November 2008, the project appears to be halted.
Sony also packaged a version of Yabasic for the PlayStation 2 with PS2 consoles in PAL territories.