Introspection
You are encouraged to solve this task according to the task description, using any language you may know.
This task asks to
- verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old.
- check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes compute abs(bloop).
Perl
Interpreter: Perl 5.x
require v5.6.1; # run time version check require 5.6.1; # ditto require 5.006_001; # ditto; preferred for backwards compatibility
Tcl
package require Tcl 8.2 ; # throws an error if older
if {[info exists bloop] && [llength [info functions abs]]} {
puts [expr abs($bloop)]
}
E
def version := interp.getProps()["e.version"]
(There is no built-in version comparison, and the author of this example assumes that implementing a version comparison algorithm isn't the point of this task.)
escape fail {
def &x := meta.getState().fetch("&bloop", fn { fail("no bloop") })
if (!x.__respondsTo("abs", 0)) { fail("no abs") }
x.abs()
}