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From: sommar@enea.UUCP
Newsgroups: comp.software-eng
Subject: Re: User-modified compilers
Message-ID: <2427@enea.UUCP>
Date: Fri, 30-Oct-87 18:10:46 EST
Article-I.D.: enea.2427
Posted: Fri Oct 30 18:10:46 1987
Date-Received: Tue, 3-Nov-87 02:17:50 EST
References: <326@moncsbruce.oz>
Reply-To: sommar@enea.UUCP(Erland Sommarskog)
Followup-To: comp.software-eng
Organization: ENEA DATA Svenska AB, Sweden
Lines: 40

conybear@moncsbruce.oz (Roland Conybeare) writes:
>   For example,  suppose I want to allocate space on the stack,  but I don't
>know how much space will be required until runtime (this is very important
>if I want to implement function calls efficiently in an interpreter,  or
>write a B-tree where the user provides the size of the elements to be stored
>in each B-tree).  
>   How do I proceed?  If the language does not provide this facility and
>gives me no way around its restrictions, then I must find another
>solution within the language, and this may be a high price to pay 

If this is important to you, use a language which helps you do this.
Assembler if you can live without range checking. Perhaps you can do it
in C. (I don't speak C, so I don't know)
  If you prefer programming in a controlled way, languages like Simula 
and Ada premit declaring arrays with the size set at run-time. Whether 
you will get an efficient program, using these languages depends on the 
*compiler*, not the language itself.

>  I also propose that our compilers should be extensible.  My ideal compiler
>would look like one of today's compilers, but decomposed into a set of modules
>with explicit interfaces.  Some modules would describe how to compile builtin
>types.  If I did not like the compiler's code generation for floating point
>numbers,  I could reimplement the appropriate module.  If I felt that complex
>numbers were essential, I could implement them.  While much of this
>can be done using user-defined types and functions, the important thing is
>that if I have control over my types' compilation then I also control their
>implementation.

Seems like some people have all time in the world. But if you are that
lucky, why don't you write your own compiler? The notion of a user-
modifyable compiler just gives me headaches having to read the manual 
for it. And must say that I believe that we programmers would be
more productive than all wasting our time modifying the same compiler.


-- 
Erland Sommarskog       
ENEA Data, Stockholm    
sommar@enea.UUCP        
                    It could have been worse; it could have been Pepsi.