Re: Single Pass Modula-2 Compiler

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3 total messages Started by haynes Tue, 14 Oct 1986 23:28

#576

Author: haynes
Date: Tue, 14 Oct 1986 23:28

27 lines
1853 bytes

	Re: Declaration after use is an abomination, 
	    and should not bear consideration.

Yeah? And so's your mother! (Proof by assertion refuted by childish ad
hominem attack. Now that I've satisified net protocol...)

What's wrong with declaration "after use"? Especially for procedures
and the destinations of pointer types, declaration after "first
mention" is often a natural programming style. It does make single pass
compilation more difficult, sometimes impossible, and has performance
implications for any compiler that has to translate the language that
allows it. However declaration after use is not the obvious abomination
you would try to hand wave us into believing.

If claim that declaration before use results in more correct, easier to
maintain programs, I will reply that the easiest to maintain large
programs I ever worked on had all procedures declared in strict
alphabetical order. That sure made a given procedure easy to find.

One pass compilers are a boon to compiler writers and people who have
to run on small machines. For them a one pass compiler is often the
only possibility. For others who have large machines, and want an easy
to use language, but don't want to sacrifice correctness or efficient
object code, a multi-pass compiler is often the right thing.

	-- Charles

Re: Single Pass Modula-2 Compiler

#571

Author: Randy Bush
Date: Thu, 16 Oct 1986 23:20

17 lines
1127 bytes

And your mother wears combat boots!

Certainly I agree that forward reference is needed to resolve pointer
declarations.  And I agree that PIM-2.[1..3] would allow forward
reference to procedure declarations, although discussion here has not
revealed a method for one-pass compilation of such - forward declaration
being the only technique discussed so far.

What I refer to is that PIM-2[1..3] would seem to allow

  PROCEDURE A ();
  BEGIN
    x := 42
    END A;
  VAR x : CARDINAL;

randy

Re: Single Pass Modula-2 Compiler

#579

Author: Felton.pa
Date: Fri, 17 Oct 1986 21:07

13 lines
1009 bytes

	Re: Declaration after use is an abomination, 
	    and should not bear consideration.

	If you think about it, requiring that procedures be declared before
they are called is contrary to the ideals of top down programming. 
	
	
John

p.s. I know. You don't have to write the program in the same order that
it appears in the listing. But, in practice this is often the way that
it is done.

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