http://d.puremagic.com/issues/show_bug.cgi?id=5024

           Summary: Order of execution of invariant and pre/post
                    conditions
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2010-10-09 06:36:30 PDT ---
This is a D2 program that uses Contracts:


import std.c.stdio: printf;

class Foo {
    int x = 0;

    invariant() {
        printf("Foo invariant: %d\n", x);
        assert(x >= 0);
    }

    this() {
        printf("Foo constructor: %d\n", x);
        x = 0;
    }

    void setX(int newx)
        in {
            printf("Foo.setX precondition: %d\n", newx);
            assert(newx >= 0);
        } out {
            printf("Foo.setX postcondition: %d\n", x);
            assert(x == newx);
        } body {
            printf("Foo.setX body\n");
            x = newx;
        }
}

void main() {
    auto c = new Foo();
    c.setX(10);
}


This is the output of the program, DMD 2.049:

Foo constructor: 0
Foo invariant: 0
Foo.setX precondition: 10
Foo invariant: 0
Foo.setX body
Foo invariant: 10
Foo.setX postcondition: 10


But I think the Foo.setX precondition needs to run after the Foo invariant, and the Foo.setX postcondition has to run before the Foo invariant.

See bug 5023

See also bug 3578 and bug 3856

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=5024


Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |DUPLICATE


--- Comment #1 from Walter Bright <bugzilla@digitalmars.com> 2012-01-19 13:58:09 PST ---
*** This issue has been marked as a duplicate of issue 5023 ***

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=5024



--- Comment #2 from bearophile_hugs@eml.cc 2012-01-19 19:25:11 PST ---
It's not a duplicate. Issue 5023 asks to document something, and this issue asks to make that something in a different way.

A discussion thread: http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=155592

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=5024



--- Comment #3 from bearophile_hugs@eml.cc 2012-01-19 19:28:04 PST ---
Walter has said:

> My reasoning is it (1) doesn't make any difference and (2) it's always
> been like that - and if it did make a difference, it would break 10 years
> of existing code.

A note: this issue is of a list of about twenty issues that I especially care about. Essentially *all* of them are little/tiny breaking changes like this one.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------