J.2  Strings as Code

Sheerpower allows strings to contain code. This makes it easy to design and implement your own business-specific scripting languages. This simple example uses the eval() function:

a = 45
b = 10
c$ = 'a*b + pi'
declare dynamic d
d = eval(c$)
print d

The content of c$ is compiled into Sheerpower byte code at runtime and then evaluated. The result is stored into D. Because the eval() function can return any data type, depending on the string that was passed into it, D must be declared as a dynamic variable.

In special cases where a lot of code flexibility is required, Sheerpower supports "code manifestation" where entire blocks of code are compiled and executed at runtime. This is done using the execute statement:

suffix$ = '_temp'
code$ = 'for i'+suffix$ + '= 1 to 10\' +
         'print i'+suffix$ + '\next i'+suffix$
execute code$
execute 'print i_temp'

Note: The use of execute can make your code harder to maintain because the actual code does not exist until runtime. It should only be used in special cases where it is the best solution.