Interactive D?

[Oskar Linde]

bearophile wrote:
> Oskar Linde:
>> I got the idea to investigate the possibility of an interactive D 
>> interpreter. A lazy afternoon of hacking resulted in a proof of concept, 
>> and what follows is a short demo.
>> Could there be any interest in pursuing this?
> 
> A interactive shell interpreter is very useful to learn the language, and to try little snippets of code before copying them into the code. Python and Scheme programmers do it all the time, and it's one of the advantages of those languages. So I think this may become quite useful.
> How does it work? Do you use the run-time compiler lib recently announced?

I don't use exe-lib. What Burton Radons has done is seriously impressive 
and is a much bigger project than my small hack. I have constrained 
myself to using the system built-in dynamic linking tools 
(dlopen,dlclose et. al. or LoadLibrary/FreeLibrary on win32).

What the code does is basically creating some run-time d-code wrapping 
the expression together with some helpers to feed data and type 
information back and forth. It then compiles the generated code into 
object code and transforms it into a dynamic library loadable with 
dlopen. The generated library is then loaded, executed and unloaded 
within the interpreters memory space.

The "import" statement compiles the corresponding .d source file and its 
dependencies into one dynamic library per module, and then loads them 
into the interpreter. If, at any time, a .d source file is changed the 
corresponding module (and modules depending on that module) are 
unloaded, recompiled and reloaded.

Burton's approach seems very interesting though. Not primarily speed 
wise, since interactive speeds are enough for an interactive application 
and a 50 ms delay compared to Burton's 1 ms is not very noticeable. 
Instead, the major advantage of exe-lib is that it allows a much finer 
control over library loading than the blunt dlopen/LoadLibrary. For 
example, the possibility of having a callback resolving missing symbols 
would be extremely useful.

-- 
Oskar