Metaprogramming
Metaprogramming is the design of programs that generate code meant to be used
at the same of a similarly high level of abstraction as the metaprogram’s
language. For example, the popular languages Python and Javascript each provide
a built-in function called eval that takes as input a string and then tries to
interpret that string as a piece of code in the respective language (here,
“interpret” refers to immediately executing the code a high level rather than
first compiling that code to a low-level representation, usually C or
Assembly).
Metaprogramming is the ultimate abstraction tool, since (almost) any pattern of code at all can be generated by a metaprogram of the same or smaller size (asymptotically, at the very least). However, metaprogramming can also yield some severe side-effects.
- Generated code is not directly visible while programming, so there is an additional layer of obfuscation between programming and feedback.
- Metaprograms usually only have limited access to static information, which
inferred by the compiler, about the programs to be generated. On top of this,
metaprograms are not usually checked to make sure they generate valid
programs. Python and Javascript’s
evalfunction know that their argument is a string and nothing more! 3.